Russian President Dmitry Medvedev (R) is thanked by Brookings Institution President Strobe Talbott after answering questions at the think tank’s headquarters on April 13, 2010 in Washington. (Win McNamee/Getty Images)

Of all the topics the venerable Brookings Institution has examined in recent years, legalizing marijuana was rarely high on anyone’s scholarly agenda.

That changed after a November 2012 visit from a lawyer working with Peter B. Lewis, the billionaire insurance magnate who during the last years of his life made the legalization of marijuana his personal mission.

Lewis had made inroads in several states, including legalization wins in Colorado and Washington. But he was having no luck getting the Obama administration — or congressional leaders — to support his campaign. He realized, he told his top advisers, that he needed to “change the groundwater in Washington” — and to do that he reached out to Brookings and a few other Washington-based organizations.

“If you have an event at an institution like Brookings, the word spreads,” said Graham Boyd, Lewis’s longtime adviser, who represented him during that first meeting at Brookings in 2012. “Even if the material discussed doesn’t get published, if you attended one of those meetings, you were likely to mention it at a dinner party, over coffee, in a meeting with the boss.”

Brookings had co-hosted one seminar on marijuana legalization before Boyd’s visit. Soon after the meeting, Brookings emerged as a hub of research that supported the views of the legalization movement — with prominent scholars offering at least 20 seminars, papers or op-ed pieces since early 2013 considering the idea. Before his death last year, Lewis donated $500,000 to Brookings, according to officials at the think tank. Two of the scholars working on the issue said they knew Lewis was their benefactor.

The Brookings Institution has become more reliant on outside donors, including corporations, foreign governments and wealthy individuals.

“When we were able to find a funder it was, like, ‘Hell, yeah, this is just what we wanted to do,’ ” said Jonathan Rauch, a Brookings senior fellow who was among the researchers working on the issue.

Over the past decade, a new business model has taken hold at Brookings. The Washington institution renowned for impeccable research and its clout as an independent policy architect has in recent years placed an emphasis on expansion and fundraising — giving scholars a bigger role in seeking money from donors and giving donors a voice in Brookings’s research agenda.

The shift has been powered by a new era of corporate influence in Washington, in which wealthy interests outside government are looking for new avenues to reach policymakers on the inside. Lobbyists are increasingly encouraging clients to donate to Brookings and other think tanks as a way of getting researchers to spend time on the issues that donors care about. Lobbyists say they warn clients not to expect that they can dictate research results from an elite think tank such as Brookings but note that they gain a chance to make their case directly to researchers, stay in touch as papers are written and suggest participants in public forums.

By enlisting Brookings and other top-tier think tanks, “you can amplify or raise an issue,” said Ed Kutler, a senior partner at Mercury, a public affairs and lobbying firm that has developed expertise in think tanks. “You can buy attention, but not a point of view or an outcome.”

Brookings officials say that the think tank remains vigilant in protecting its scholars’ independence and that donors do not have a say in determining the outcome of research.

Founded in 1916, Brookings was Washington’s first think tank and remains very much at the heart of the city’s establishment. A University of Pennsylvania survey ranks Brookings the world’s top think tank, and for decades the institution has been a sought-after destination for senior-ranking government officials when they leave office. Its hundreds of scholars — about 150 in-house and 250 who retain nonresident affiliations — occasionally operate as unofficial government envoys who take part in delicate international diplomacy. Others produce definitive works examining Congress, the economy and American society.

In the past, Brookings was funded for the most part by no-strings-attached grants from large foundations and individual philanthropists. An endowment, unusual for a Washington think tank, provided steady interest income that supported independent research and insulated scholars from the fundraising side of the organization.

That became problematic. Foundations began to place more restrictions on their grants, part of a challenging new trend facing Brookings and other academic institutions in which donors increasingly specify their expectations as part of what they call “impact philanthropy.”

Brookings’s endowment, mean­while, was having trouble keeping up with the financial needs of the institution.

When he took over in 2002, Brookings President Strobe Talbott faced a deficit and intense competition from a growing number of Washington think tanks.

Talbott, a former journalist and Clinton administration diplomat, said in an interview that he decided then to remake Brookings with a far-reaching expansion plan that would rely on aggressive fundraising and make the institution even more influential. That plan, determined in consultation with Brookings veterans, was built on the idea that the institution, for all its effectiveness in a polarized Washington, needed to extend its reach into local communities and into foreign capitals.

The strategy of rapid growth and aggressive fundraising has proved financially successful, with annual revenue soaring from $32 million in 2003 to about $100 million in 2013, according to Brookings’s annual reports.

The additional resources have allowed Brookings to retain its primacy, even amid the national economic downturn that squeezed other academic organizations.

The strategy also led to a lesser reliance on the endowment. Brookings’s annual reports show that, as the organization has grown, income generated by the endowment has declined as a proportion of annual operating revenue — from about one-third a decade ago to 11 percent in 2013.

‘Conscious of the pressure’

Talbott said in the interview that he is “acutely conscious of the pressure that our growth and ambition and the scope of our programming puts on our institution.” He said he deliberately kept fundraising pressure limited “to a relatively small group who are prepared to deal with the challenge,” a group that includes top executives and the directors of Brookings’s five major academic programs and 17 specialty centers. Scholars are encouraged to interact with donors, Talbott said, but they are not required to do so.

“We don’t ever want to be in the position of telling someone who is an expert in their field that we can’t hire you or we can’t keep you because you don’t want to do fundraising,” Talbott said.

Brookings officials said they have created a strong internal system to maintain independence. And outside analysts credit Brookings’s conflict-of-interest and disclosure standards, which they say exceed those of other think tanks.

Brookings officials note that research reports include a disclaimer that “analysis and recommendations are not determined or influenced by any donation.” Guidelines require most paid employees to annually list conflicts of interest on forms that are reviewed internally.

In addition, Brookings officials said, no single donor provides more than 2.5 percent of the overall budget, limiting the influence that any one funder can have on the institution.

Yet a Washington Post review of a few key issue areas found that Brookings’s public seminars, research papers, congressional testimony and op-eds often correspond to the interests of donors.

Heirs to the Wal-Mart fortune, who have poured money into school initiatives challenging the power of teachers unions, have joined their ideological allies in giving millions of dollars to support Brookings’s education policy center — whose scholars regularly adopt market-oriented stances­ on key issues.

Energy companies have escalated their giving to Brookings in recent years, and its Energy Security Initiative has built a team of experts made up in large part of individuals with oil and utility industry ties.

Brookings satellite centers can serve as additional sources­ of revenue. The Brookings Doha Center, an arm of the think tank in Qatar’s capital that focuses on Middle East issues, is funded largely by the Qatari government, which has pledged $21.6 million to Brookings since 2011. Brookings’s only U.S. office outside Washington is at the University of Nevada at Las Vegas and is supported in part by two major local industries, gold mining and casinos.

While the bulk of Brookings’s work focuses on broad policy issues, the institution has on occasion produced reports that address specific requests from individual donors, although officials say such work always serves a broader purpose.

Atlanta-area boosters seeking to build a rail line between the city and Macon, for instance, agreed to pay Brookings and contributing researchers $200,000 in 2010 for an economic impact study and received a report forecasting large benefits from the project — a study that Brookings officials later said failed to meet the institution’s standards because it was not properly reviewed.

Brookings officials say there are many examples in which the think tank has declined offers to conduct research and cases­ in which donors withdrew their money because they disagreed with Brookings’s activities.

In one instance, Brookings lost funding from a longtime Turkish donor who had objected to an event that included a Kurdish official, said David Nassar, Brookings vice president for communications.

A Washington Post analysis of donor lists published by Brookings in its annual reports over 11 years found that the institution has grown more reliant on corporations, wealthy individuals and foreign entities.

Corporations made up 25 percent of Brookings’s donors giving at least $50,000 in 2013, up from 7 percent in 2003, the analysis found. The proportion of donors at that level coming from overseas, including foreign governments and trade associations, rose from 6 percent to 22 percent in that period. Separately, the analysis showed a substantial increase over that time in the percentage of gifts that came from corporate and foreign donors.

Brookings officials dispute The Post’s findings, saying the annual reports do not provide a realistic picture of the center’s funding. Rather than looking at cash gifts, which are disclosed in ranges in the annual reports under the headline “Honor Roll of Contributors,” officials said a more accurate view of the center’s finances­ would come from an analysis of annual operating ex­penses.

Talbott said relying on Brookings’s publicly disclosed annual reports can be misleading because some cash gifts listed each year are intended to be spent over multiple years.

“By focusing solely on cash received in individual years, The Washington Post presents an inaccurate picture of Brookings’ growth,” Talbott said in an e-mailed statement.

This week, Brookings provided summarized expense data for four years, 2011 to 2014, that showed modest growth in the proportion of support from corporations and foreign governments.

But the newly posted numbers probably understate the total spending derived from those contribution types because, according to a Brookings official, an additional category called “Contributions and Endowment” may include a portion of funds from corporations and other sources. The official said the category is unlikely to include foreign government funds.

Brookings did not provide data from previous years, saying that the center had changed accounting systems and that the information was not readily available.

Brookings also declined to provide more-specific data on contributions beyond the annual reports, which typically list donors in ranges of up to “$1 million and above.” Officials showed The Post a one-page chart analyzing cash received by donor type, which showed fluctuations from year to year in the proportion of overall gifts that came from corporations and foreign governments. Cash from foreign governments, for instance, accounted for 8 percent of total cash revenue in 2005 and 14 percent in 2014, according to the Brookings cash chart, while the corporate cash figure was 16 percent in 2005 and 20 percent in 2014.

James McGann, director of the Think Tanks and Civil Societies Program at the University of Pennsylvania, said Brookings provides an unusual level of disclosure regarding its funding and relatively strong internal ethics guidelines. He said Brookings’s broad donor base gives it a higher level of protection from funders’ influence than other think tanks.

Still, McGann said that contributors to think tanks are increasingly “determining the agenda of research institutions they support,” McGann said. “They become interlopers and can have a highly distorting effect.”

A $600 million drive

The pressure to raise money is growing more intense at Brookings, with an ongoing drive to raise $600 million. Much of the money would be earmarked for the endowment, which could reduce future dependence on outside donors. Talbott said Brookings was seeking multiyear gift pledges with little or no restrictions, a move he said would further ease the annual fundraising demands.

Some Brookings scholars say that the fundraising imperative has changed the environment, as they are asked to review the costs and financial benefits of their work and, in some cases, to spend time attending seminars and receptions with donors.

Researchers mingle with top-level donors at “Brookings in the Hamptons” and private travel seminars, some to overseas locales, including China, India and the Middle East. Lobbyists from Washington’s premier firms show up regularly, with clients in tow to meet with scholars and institution luminaries.

The ambitious expansion and attention to fundraising has prompted internal debate at Brookings, with some who work there feeling anxious and others satisfied that the institution is more secure and that its standards remain high.

“My assessment is that Brookings has come through this with its integrity intact,” said Thomas Mann, a Brookings political scientist, who applauds Talbott’s growth strategy.

Tom Loveless, an education expert at Brookings for the past 15 years, has recently produced research critical of the Common Core State Standards — putting his views at odds with a major donor, the Bill & Melinda Gates Foundation, which has been the primary backer of the initiative.

Loveless said he has “never had my independence compromised at Brookings.” Yet, he added, while donors may not meddle in specific papers at Brookings, the new funding imperative at think tanks gives philanthropists and other wealthy interests power to determine the broader research agenda.

“It limits the topics of research considerably, and it is going to diminish public confidence in our work,” he said.

From the outside, said Randi Weingarten, president of the American Federation of Teachers, it appears that Brookings no longer behaves like the independent academic institution it once was.

Weingarten, who leads one of the country’s two major teachers unions, said she and her predecessors used to be regularly invited guests at Brookings forums on education policy. But now, with the center’s scholars largely taking stands that run counter to the unions’ views, Weingarten said she is rarely on the Brookings invite list.

“We have sadly had to just give up on Brookings being the kind of institution it used to be,” she said. “They are no longer a real think tank exploring ideas and enabling the free expression of those ideas. You see a clear shift away from that in the past several years.”

The head of Brookings’s education policy center, Grover J. “Russ’’ Whitehurst, disputed the notion that his group of seven scholars and staff had any bias. He said he hoped Weingarten and other union officials would re­engage with Brookings.

“If Randi wants to give us a pot of money to investigate a topic that is important to her, I’d be happy to take it and stand by the findings of our work,” he said.

Sponsored research

At an event in Brookings’s auditorium last month, a group of energy experts took the stage and made the case for why the United States should lift its decades-old embargo on exporting oil.

Their unanimous view, presented during a forum hosted by Brookings’s Energy Security Initiative, echoed the position now being pressed by industry lobbyists in Washington.

Unstated at the event was the extent to which the oil industry has escalated its giving to Brookings in recent years.

Energy companies such as Chevron and Exxon Mobil are now among the major donors to Brookings, providing at least $2.1 million since 2011, according to Brookings’s annual reports. In addition, most of the experts working on the Brookings energy security program have worked for oil firms or utilities — including one nonresident scholar, featured at last month’s event, whose consulting firm works for oil and gas industry clients.

The event illustrates a quandary facing Brookings, which has become more influential in its ability to shift national debates while also drawing complaints that its research conclusions match the views of its donors.

A number of recent Brookings studies have been singled out for criticism by academics and others, some of whom attribute the research results to Brookings’s association with corporate donors and other wealthy interests.

One study, released in June, analyzed Federal Reserve Board data that tracks student debt and income levels in young households to conclude that typical student borrowers were no worse off now than they were a decade ago and that reports of a student debt crisis may be overblown.

The study contradicted arguments from critics of the for-profit student-loan industry, including Sen. Elizabeth Warren (D-Mass.), who has pushed for federal relief of a debt burden that she has said “crushes­ millions of young people and has started to weigh down the entire economy.”

Warren’s legislative staff later noted that Federal Reserve Chair Janet L. Yellen cited the same database studied by Brookings to reach a wholly different conclusion — warning in an October speech of the dire consequences from a “dramatic increase” in student debt, particularly for low-income families. Yellen expressed “fear” about “the large and growing burden” of student debt.

Warren declined to comment on the Brookings reports, but she called for greater transparency so the public can assess the “independence, or lack of independence, of the research from think tanks.”

Michael Simkovic, a visiting associate professor of law at the University of North Carolina at Chapel Hill and an expert on lending issues, said that if Brookings’s reports on student debt were to dictate policy, they would “boost the profits of the student lenders like Sallie Mae.”

Critics pointed to a potential tie between Brookings and the lending industry: $1.9 million in donations since 2009 from the Lumina Foundation, which was created in 2000 when USA Group, then the largest administrator of private student loans, sold its assets to Sallie Mae. The donation figure was tabulated by the Foundation Center, a research group that tracks philanthropic giving.

Two former Sallie Mae board members sit as directors of Lu­mina.

Lumina did not underwrite the June study, according to co-authors Matthew M. Chingos and Beth Akers. But Chingos’s curriculum vitae says Lumina has given him and Akers hundreds of thousands of dollars in research grants since 2011. Chingos said much of that grant money has supported work on a project that could lead students to “complete college more quickly and therefore take on less debt.”

Chingos and Akers said that there was no interference with their work by any donors and that they were themselves surprised at what they found in the data. Chingos said he didn’t know until after one of their papers was published this year that Lumina had been initially funded by the student-loan industry.

Both said they stood by their work, and Whitehurst, the director of the Brookings education center, said Chingos and Akers were superb scholars who had conducted ground­breaking, high-quality and independent work.

“I couldn’t be prouder of these two young scholars,” he said. “They have changed the whole conversation on student loans.”

Lumina’s director of strategy, Zakiya Smith, said suggestions of meddling were “mind-boggling” and noted that Lumina funds a broad range of researchers.

A second controversial line of research, published in 2012 and 2013, makes points that have been used by supporters of expanding skilled foreign-worker visas.

That position is a key priority being pushed by lobbyists for the country’s high-tech industry.

Microsoft and other technology firms have increased their giving to Brookings in recent years. A “donor profile” of Microsoft on the Brookings Web site describes the company as “deeply engaged” in research and includes a quote from Talbott lauding Microsoft executives as “a terrific source of strategic ideas that help inform our research.”

Brookings officials said that only a small fraction of Microsoft’s donation of more than $1 million in cash and software to the institution in 2013 went to the Metropolitan Policy Program, which produced papers on foreign-worker visas and the need for more scientists and engineers. They said Microsoft funding was not used at all to support the controversial visa studies.

Still, the findings of two Brookings reports on the issue drew criticism from some academics and advocates for U.S. engineers, who noted that tech companies were using Brookings’s scholarship to lobby for an expansion of the visa program.

In one study, critics suggested Brookings made a methodological error that under­stated the extent to which the program is used by overseas out­sourcing firms. The use of these visas by foreign firms has been a focus of debate on Capitol Hill, with critics charging that the program enables companies to import cheap labor and displace American workers.

In another case, critics said Brookings used flawed assumptions to conclude that foreign workers were not undercutting Americans’ wages.

Ron Hira, a Howard University professor who has been critical of the visa program, said Brookings’s work on the issue is “closely aligned with the talking points of the tech industry’s lobbying efforts.” Hira, who has been an officer of the Institute of Electrical and Electronics Engineers, which has lobbied against expanding the visa program, said the Brookings scholars “made many poor research design choices, which heavily bias their results.”

Alan Berube, the deputy director of the program that produced the research, firmly rejected the criticism. He said the Brookings studies used data correctly and made one minor correction after Hira, who had been sent an advance copy of the wages­ study, pointed out an error.

“Our researchers have fully responded to the methodological charges­ that Hira and other professional critics of the H-1B program have made,” Berube said. “Any suggestion that industry or other interest groups influenced this research is simply baseless.”

He said the papers reflected Brookings’s ability to contribute high-quality work on a complex topic.

“We conduct objective, dispassionate research on issues that often inspire passion and conflict,” Berube said. He added that the examination of the visa program “injected timely analysis into an important policy debate without bias toward any side.”

Brookings’s ties to the energy industry were evident during last month’s forum on oil exports with the presence on stage of one of its most visible scholars.

David Goldwyn — who leads his own energy consulting firm while he also writes research papers and testifies before congressional committees — laid out the case for allowing exports as part of a panel discussion moderated by Talbott.

On the Brookings Web site and in congressional testimony, Goldwyn is identified as a nonresident senior fellow at Brookings and as president of Goldwyn Global Strategies.

He said in response to questions that his client list includes oil and gas firms, but he declined to name them. He said that “my views do not always align with those of my clients,” noting that he has backed a carbon tax and greater industry transparency.

The director of the Brookings energy program, Charles K. Ebinger, said in an interview that he did not think public disclosure of Goldwyn’s clients was needed.

“David is so well known we thought everybody knew he had the industry contacts,” Ebinger said.

Brookings officials said that their energy experts do disagree at times.

Nassar, the spokesman, pointed to recent disputes over “important ­nuances” within the debate over policies regarding exports of liquefied natural gas. Ebinger said a number of scholars have “researched the relationship between energy extraction and usage and their impacts on climate change.”

In some cases, donors have requested scholarly attention to relatively narrow topics.

In 2009 and 2010, after a spike in energy demand in the United Arab Emirates, that country “sponsored” a project in which Brookings experts studied the potential for new nuclear power plants in the Persian Gulf, Ebinger said.

Starting in 2013, Duke Energy provided a $25,000 gift to create the Global Electricity and Technology Roundtable, a private forum at Brookings in which industry officials mix with regulators.

In the cases­ of the UAE and Duke sponsorships, Brookings officials said the projects have resulted in quality work that does not necessarily favor the interests of the donors.

Brookings officials said they failed to adequately review the findings in a different area — the study, funded by Atlanta-area boosters, of the proposed Atlanta-Macon rail line.

The think tank was paid $60,000, its share of the overall $200,000 fee for the report, which was distributed in Georgia emblazoned with the Brookings logo, although it was never published on Brookings’s Web site.

The Brookings report describes the project in generally glowing terms, calling rail “the most important transportation infrastructure for metro Atlanta and Macon in the early 21st century.”

Bruce Katz, director of Brookings’s Metropolitan Policy Program, which conducted the study, said the project was so small that he was not aware of it until contacted by The Post. Katz said it was an “objective analysis that in fact disclosed weaknesses in the proponents’ case for the railway.” Yet, he said, the report had not met Brookings’s standards for review. He described the rail study as an isolated case.

Mutual benefits

The ties between Brookings and Qatar illustrate the mutual benefits that accrue to the think tank and its donors.

While Brookings gained a revenue stream, Qatar, a Persian Gulf state eager to emerge from Saudi Arabia’s shadow, has used Brookings and other U.S. academic institutions to boost the country’s credibility on the world stage.

The center’s director in 2009 told visiting U.S. officials that Qataris had told him that they viewed the think tank’s conferences as part of a broader security strategy that included the presence of U.S. military bases, according to a leaked State Department cable obtained by the Web site WikiLeaks.

“We think of the conferences as our aircraft carriers, and the military bases­ as our nuclear weapons,” one Qatari told the center director, according to the cable.

The connection has come under fire from some U.S. allies in the region in recent months, as Qatar has drawn attention for support of Hamas and other militant groups. Aspects of Brookings’s financial ties with Qatar were reported in the New York Times in a September article on think tanks’ reliance on foreign government support.

One senior Israeli official, who spoke to The Post on the condition of anonymity because of the sensitivity of the subject, said Brookings’s funding from Doha “has definitely caused some parts of the [Israeli] government to look skeptically on the work of Brookings.”

“It is still widely seen as the leading think tank, or one of them, in Washington,” the official added. “But it definitely makes you look at the institution differently.”

Brookings officials say the Qatari money pays for the Doha Center and for a project based in Washington that studies the Islamic world. They say that the relationship with Qatar has not violated the independence of any scholars and that the Doha Center gives Brookings a valuable perch to study an important region.

“I don’t want to give the impression that because we got funding from Qatar we are in their corner. We are not,” said Martin Indyk, the director of Brookings’s Foreign Policy Program and a former U.S. ambassador to Israel in the Clinton administration. “They do some bad things, but in terms of what they do for Brookings and what Brookings is able to do with their funding, I think that it provides a public good.”

The skepticism among some Israel supporters has grown as one of the other major funders of Brookings’s Middle East research, pro-Israel billionaire Haim Saban, reduces his support.

Saban, whose name has graced Brookings’s Center for Middle East Policy, moved quietly this year to remove his name from the official title.

Brookings officials said he will continue funding a series of policy forums. They said that while Saban clearly has strong pro-Israel views, his opinions also never influenced Brookings’s research. But they declined to say what proportion of overall funding for the Middle East Policy Center will come from Qatar now that Saban is apparently scaling back.

Saban did not respond to requests for comment.

The marijuana debate

Lewis, who died last November at the age of 80, saw Brookings as part of the remedy for his effort to win broad support for marijuana legalization, according to his longtime adviser, Boyd.

The billionaire, who spent as much as $40 million bankrolling marijuana ballot initiatives around the country, was frustrated by the Obama administration’s continued resistance to his idea. In 2010, on the eve of a significant California legalization vote, Attorney General Eric H. Holder Jr. cautioned that the Justice Department would “vigorously enforce” federal marijuana statutes “even if such activities were permitted under state law.”

Lewis sought to draw Brookings into the fray “because they have a reputation for independence, integrity and quality,” Boyd said.

Boyd’s 2012 meeting with Brookings took place days after two states, Colorado and Washington, had voted to legalize pot. Speaking on behalf of Lewis, Boyd suggested that scholars focus on whether the federal government should block state policy initiatives — a way to argue for Washington to let the marijuana-legalization movement proceed without conflict.

The meeting and Lewis’s eventual donation coincided with a flurry of activity at Brookings on the issue, much of which focused on ways the federal government could respond and allow new state laws to proceed.

Events were led by some of Brookings’s best-known scholars, including E.J. Dionne, Stuart Taylor Jr. and, from the beginning, Rauch, who first became interested in the issue in early 2012. Dionne is also a Washington Post columnist.

Taylor said he was under no pressure as he studied and wrote about federal issues related to legalization. But he recalled being told before starting that Lewis was the donor.

“My first thought was that I probably would not want to do this if I were a militant anti-legalizer,” Taylor said in a recent interview. “Nobody told me this. I just thought that it is not reasonable to expect donors to provide funds to be used in ways that they would deplore — just as I probably would not propose to The Washington Post a negative op-ed about”

The Post is owned by Amazon founder and chief executive Jeffrey P. Bezos.

Boyd said that his early conversations with Brookings did not include discussion of a donation.

The money came in 2013 from Lewis and other sources. In addition to Lewis’s $500,000 gift, his ex-wife, Toby, an ally in the marijuana cause, gave an additional $10,000 to $25,000.

Alice Crites contributed to this report.