K Street is playing an increasingly central role in the 2012 presidential race, as hundreds of lobbyists representing some of the world’s largest corporations and trade groups pour money into Republican coffers.

The main beneficiary so far is Mitt Romney, the former Massachusetts governor and equity-fund executive, who is banking on strong support from the business community to propel his White House bid.

More than 100 registered lobbyists have contributed to Romney, giving nearly $200,000 in direct donations, according to a Washington Post analysis of donor and lobbying records. A team of lobbyist fundraisers has also bundled together nearly $1 million in contributions for Romney’s campaign, disclosure records show.

Texas Gov. Rick Perry, who entered the race in August, took in at least $72,000 in contributions from 42 lobbyists through September, plus $77,000 bundled by a bank executive. Dozens of Washington lobbyists have also given money to trailing candidates Jon Huntsman Jr., Newt Gingrich and Rick Santorum, the analysis shows.

The early pace of donations underscores the pivotal importance that K Street donors are likely to play in driving up spending during the 2012 elections, which are widely expected to be the most expensive in U.S. history. Republicans are hoping that strong support from lobbyists and corporate political action committees will help them compete with President Obama’s formidable fundraising operation.

As he did in 2008, Obama has made a point of refusing to accept donations from lobbyists or corporate PACs, and his campaign has repeatedly portrayed Republicans as beholden to Wall Street and other well-funded interests. But Obama faced his own criticism this week after hiring a former corporate lobbyist as a senior campaign adviser.

The lobbyists who have donated to GOP candidates so far represent a broad swath of corporate interests, including technology firms lobbying for a tax holiday on overseas profits and oil companies hoping to preserve lucrative tax breaks on energy.

On Wednesday morning, for example, Romney attended a breakfast fundraiser at the American Trucking Association sponsored by more than a dozen K Street heavy-hitters. Hosts included longtime GOP fundraiser Wayne Berman, who represents the American Petroleum Institute and many others; GOP lobbyist Mark Isakowitz, whose lengthy client list includes banks, oil companies and technology firms; and Alex Mistri of the Glover Park Group, which briefly represented Solyndra, the solar-energy firm that went bankrupt after getting a $530 million government loan guarantee.

Perry, whose financial base lies in the oil fields of Texas, also has worked to make inroads into Washington’s lobbying community, recruiting donors to help bundle together contributions and seeking advice from K Street professionals. Last week, Perry held a series of private policy meetings with about 45 lobbyists, trade group executives and conservative leaders at the National Association of Wholesaler Distributors, whose president and government relations chief are key Perry fundraisers.

Donors said in interviews that it is natural for industry lobbyists to back Romney, Perry or other Republicans, given the party’s traditional image as friendly to business. Most lobbyists say their decision to help raise money for candidates has no connection with their corporate clients, many of which are steering clear of the GOP primary contest.

Some K Street firms are divided on which candidate to support: Although Isakowitz supports Romney, for example, his partner at Fierce, Isakowitz & Blalock, Kirk Blalock, is helping raise money for Perry.

“I was a Republican before I was a lobbyist,” said Blalock, who represents dozens of major corporations including BP, Coca-Cola and Time Warner. “For me it’s about working for a cause I believe in and not about my business of lobbying.”

David Donnelly of the Public Campaign Action Fund, which favors public financing of elections, said such claims “ring hollow” because of the pivotal role played by lobbyists in raising money for politicians.

“These lobbyist donors get an immense of amount of access and influence over elected officials, and the rest of us get one lousy vote,” Donnelly said. “It is a business model that relies on lobbyists making campaign contributions, raising money for candidates and being in the most helpful position they can be in to benefit their clients down the line.”

Under recent reforms, which were co-sponsored by then-Sen. Barack Obama (Ill.), presidential candidates are required to identify any lobbyists who act as campaign bundlers, gathering together donations from friends and associates. But lobbyists who merely host a fundraiser or contribute individually to campaigns are not required to be identified as lobbyists in reports to the Federal Election Commission.

The Post analysis cross-matched names in the FEC’s contributions database with lobbying disclosure records filed in Congress to identify K Street donors. The total number of lobbyist donors is almost certainly higher.

Obama’s practice of refusing lobbyist contributions fits into a broader goal of seeking to curb the influence of special interests in Washington. After The Post inquired this week about two lobbyists who gave to the campaign, spokesman Ben LaBolt said the contributions would be returned.

The lines separating former and current lobbyists are often thin: One supporter terminated his lobbying registration on behalf of a Japanese insurance association on April 18, then gave Obama $900 on April 20.

The Obama campaign came under fire from environmentalists and watchdog groups this week for hiring former lobbyist Broderick Johnson as a senior adviser. Before leaving the Bryan Cave firm in April, Johnson had a decade-long career representing dozens of clients including TransCanada, which is seeking U.S. approval for a controversial oil pipeline from Alberta to Texas.

LaBolt said Johnson will refrain from any issues involving past clients.

“For years the President has fought to ensure that Washington lobbyists don’t have undue influence over the policymaking process,” LaBolt said in a statement. “There’s no doubt that special interests are pouring contributions into the coffers of our potential opponents and their allies because they believe that large corporations and millionaires and billionaires should get tax cuts instead of the middle class and that Wall Street should be able write its own rules again.”

Many GOP lobbyists and campaign aides bristle at such rhetoric and accuse Obama of hypocrisy. Perry spokesman Ray Sullivan said Obama “has already broken his own policies when it comes to lobbyists,” pointing to the campaign’s hiring of Johnson.

“All Rick Perry donors must comply with the same contribution limits and federal disclosure rules and we respect that,” Sullivan said. “Governor Perry makes policy decision based on his conservative philosophy and on what’s best for his constituents.”

Cultivating donors on K Street has been central to Romney’s fundraising efforts, aimed in part at cementing his reputation as the candidate of establishment Republicans. One key fundraiser this year was a “Lawyers for Romney” luncheon at Patton Boggs, Washington’s largest lobbying firm with $40 million in billings last year. Hosts including former senator Trent Lott (R-Miss.) raised $5,000 or more, with individual donations starting at $1,000, according to an invitation.

Romney’s top lobbyist fundraiser is Patrick J. Durkin, managing director of Barclays Capital, who raised $355,000 through September, disclosures show.

“People who contribute to Mitt Romney’s campaign do so because they support Mitt’s conservative agenda to create jobs and grow the economy,” campaign spokeswoman Andrea Saul said.

Not all lobbyists involved in the campaigns think of themselves as part of K Street. David Beightol of Dutko Grayling said he is primarily a state-level consultant who only registers as a lobbyist “out of an abundance of caution.” Beightol has raised just under $90,000 for Romney.

“It’s mostly posturing,” Beightol said of Democratic complaints about lobbyist fundraising. “It’s just a political game.”

Read more on PostPolitics.com

Perry skipping debates? Bad idea.

Rubio on GOP ticket could be risky

Chelsea-for-Congress talk quashed

Violent Occupy clashes could hurt Dems