Rep. Darrell Issa is trying to make good on his promise to keep close tabs on the Obama administration.

Since assuming the chairmanship of the House Oversight and Government Reform Committee in January 2011, the California Republican has held hundreds of hearings, made more than 700 requests for information and issued almost two dozen subpoenas.

But for every line of inquiry that led to a public hearing or legislation, administration supporters and critics alike complain privately — White House and agency officials especially fear upsetting the chairman — that many of the efforts by Issa’s staff resulted in no follow-ups, no hearings or no reports. Essentially, some complain, there have been too many instances in which there was more show than substance.

Eric Schultz, a White House spokesman hired last year to handle the crush of media requests anticipated by GOP oversight investigations, puts it delicately.

The White House has cooperated “with legitimate congressional requests for information,” he said. But “we believe that neither political motivations nor political theater should drive congressional oversight.”

Issa issued 22 subpoenas and published 11 investigative GOP staff reports, and the panel sent 748 letters seeking information from the White House and federal agencies in his first year, according to the panel’s records.

Some Issa hearings have had their share of drama. Last week, Democrats walked out of a session when Issa blocked testimony from a woman who supported the Obama administration’s decision to require insurance companies to pay for the contraceptives of employees at faith-based institutions that object to them. Issa said the Georgetown University law school student did not have the appropriate credentials to testify at a hearing regarding perceived threats to religious freedom.

One issue, however, that has earned the chairman and his panel bipartisan kudos — and significant headlines — is the Department of Justice’s “Operation Fast and Furious” gun debacle.

Whether he strikes an administration nerve or not, Issa isn’t apologetic for his aggressive style.

“Do we send a lot of letters out? Yes,” he said recently. “When we hear about it, we send letters. And when we get answers, we very quickly say, ‘We’re all set, thank you very much, we’re done.’ ”

In addition, Issa and his aides noted that the administration faced virtually no serious congressional oversight in its first two years, when Congress was controlled by Democrats.

Administration officials provided a list of dozens of oversight panel requests that appear to have fallen flat. The committee sought information on the White House’s ties to Google after a former company official who had joined the administration used his personal Gmail account to e-mail former colleagues. Republican committee staffers later pressed federal agencies to detail how quickly officials granted Freedom of Information Act requests. Issa also inquired about President Obama’s meetings with political advisers and about why Federal Communications Commission Chairman Julius Genachowski visited the White House so frequently.

Officials complained that the requests required compiling hundreds, if not thousands, of e-mails and documents.

At the Energy Department, officials said Issa’s panel sent 18 separate letters seeking information on department policy and launched 11 investigations. Some inquiries focused on the administration’s decision to grant loans to the now-bankrupt Solyndra energy company. The department has provided more than 170,700 pages of information to Issa andexpects it will take more than a year to provide more than 1 million pages of requested documents, administration officials said.

Rep. Jason Chaffetz (R-Utah), a key Issa ally, defended the chairman’s strategy.

“You think something’s there, it doesn’t pan out, you move on,” he said. “You get a lot of whistleblowers who raise questions, and with limited resources, you have to figure out where you’re going to allocate resources.”

The committee’s “Fast and Furious” probe prompted most of the 43 requests for information from the Department of Justice.Issa said he launched the investigation only after the DOJ and the White House rebuffed requests for information by Sen. Charles E. Grassley (R-Iowa), the ranking member on the Senate Judiciary Committee.

Despite contentious exchanges with some GOP lawmakers at a Feb. 2 hearing on the issue, Attorney General Eric H. Holder Jr. said, “The questions that you’ve asked — they’ve been tough, they’ve been fair.”

But Rep. Elijah E. Cummings (D-Md.), the panel’s ranking member, faulted Issa for permitting Republican committee members to air allegations against Holder and other federal officials who were still under investigation or that were previously disproved. Though he supports the “Fast and Furious” inquiry, Cummings said: “I want people to automatically assume that we’re operating almost on level with a federal court, where there’s a tremendous amount of respect. When there are allegations made and then they’re not proven, I think that it hurts every member of the committee.”

In his first year, Issa and his seven subcommittee chairmen led more than 120 hearings, according to committee staffers, far short of the seven-hearings-per-week vow he made before taking over. The number puts him short of former representative Thomas M. Davis III (R-Va.), who ran the panel during the middle of George W. Bush’s presidential term, and ahead of Rep. Henry A. Waxman (D-Calif.), who chaired the committee during Bush’s final years in office.

Rep. Gerald E. Connolly (D-Va.), a committee member, said Issa’s “peripatetic attention span” and tendency to quickly move on after attracting attention for a new line of inquiry hampers serious oversight of government management concerns.

“He’s failed to foster bipartisanship,” Connolly said. “There had been cooperation before. I don’t think it’s impossible for Darrell to recapture that, but a lot of damage has been done.”

Rep. Patrick T. McHenry (R-N.C.), who chairs the panel’s subcommittee on financial services, however, credits Issa with “very methodical oversight that’s been lacking in the last decade in Congress on regulations.”

And Davis, whom Issa considers a mentor, praised the chairman’s first year. “He’s been very careful about the investigations he’s picked,” Davis said.

In his second year, Issa said he is forging ahead on a host of issues, including Obama’s plans to reorganize trade- and commerce-related agencies.

“Real reorganization takes time, it takes buy-in, historically, from Congress and the administration,” Issa said. “It takes a willingness to understand that the upheaval has to be far more worthwhile.”

“I was sent to Congress to be a jack-of-all-trades and a master of as many as I could be,” he added. “I didn’t come to Congress for one thing. I came to try to leave our country better by being here, so I’m never apologetic for taking on as many diverse issues as I can.”