WASHINGTON -- Sen. Barack Obama credits his presidential campaign with creating a "parallel public financing system" built on a wave of modest donations from homemakers and high school teachers. Small givers, he said at a fund-raiser this week, "will have as much access and influence over the course and direction of our campaign that has traditionally been reserved for the wealthy and the powerful."

But those with wealth and power also have played a critical role in creating Mr. Obama's record-breaking fund-raising machine, and their generosity has earned them a prominent voice in shaping his campaign. Seventy-nine "bundlers," five of them billionaires, have tapped their personal networks to raise at least $200,000 each. They have helped the campaign recruit more than 27,000 donors to write checks for $2,300, the maximum allowed. Donors who have given more than $200 account for about half of Mr. Obama's total haul of nearly $240 million.

Mr. Obama's success in assembling bundlers offers another perspective on a campaign that promotes itself as a grass-roots effort. While the senator from Illinois has had unprecedented success generating small donations, many made online, the work of bundlers first signaled the seriousness of his candidacy a year ago.

The bundler list also sheds light on those who might seek to influence an Obama White House. It includes traditional Democratic givers -- Hollywood, trial lawyers and Wall Street -- and newcomers such as young hedge fund executives, Silicon Valley entrepreneurs, Chicago-based developers and members of the black business elite. One-third had never contributed to a presidential campaign, much less raised money.

The list includes partners from 18 top law firms, 21 Wall Street executives and power brokers from Fortune 500 companies. California is the top source, with 19 bundlers. Illinois and Washington, D.C., have six, and five hail from New York.

Among the group are businessmen such as Kenneth Griffin, a famously private 39-year-old billionaire who threw his support behind Mr. Obama's presidential campaign just as he hired a team of lobbyists to urge Congress to preserve a lucrative tax loophole.

A year ago, Mr. Griffin invited Mr. Obama to speak to employees of his Chicago hedge fund, Citadel Investment Group, and in subsequent months, employees and their families gave the candidate nearly $200,000. Mr. Griffin had previously backed Republicans, including Mr. Obama's initial U.S. Senate opponent.

Mr. Obama resisted Citadel's lobbying push, but a hedge fund executive who knows Mr. Griffin said he suspects Mr. Griffin's continued support owes to more than a desire to sway the senator on the tax issue. "Ken's a smart guy, and I guess he's done the math and decided that Barack is the best candidate," said Daniel Loeb, the chief executive of Third Point Management in New York.

Several on Mr. Obama's list at least appear to have interests that stand in conflict with his platform. There is the billionaire casino developer who plans to put a slot machine parlor in Philadelphia; Mr. Obama has decried gambling for its steep "moral and social cost." And there is the director of General Dynamics, the military supplier that has seen profits soar since the onset of the Iraq war and that has benefited from at least one Obama earmark.

The use of bundlers was perfected by George W. Bush, who in 2000 and 2004 set some fund-raising records that Mr. Obama has shattered. Mr. Bush established a competitive hierarchy of "Rangers" and "Pioneers," with tracking numbers to monitor fund-raisers' progress and silver cuff links and belt buckles for high achievers.

Mr. Obama's bundlers help make up a more loosely defined "national finance committee," whose members are made to feel part of the campaign's inner workings through weekly conference calls and quarterly meetings at which they quiz the candidate or his strategists.

More than 100 of Mr. Bush's 246 Pioneers in 2000 received an administration job, and 23 became ambassadors. Mr. Obama's fund-raisers say they see their work more selflessly.

"There's nobody with their hand out," said Boston financier Alan Solomont, who heads Mr. Obama's Northeast fund raising. "People are doing this because they believe in this candidate."

The campaign maintains that fund-raising success among average Americans has lessened reliance on big donors. Donations of less than $200 account for nearly half of Mr. Obama's contributions, compared with a third of Mrs. Clinton's and a quarter of Sen. John McCain's, according to the Campaign Finance Institute. More than 1 million people have given money to Mr. Obama's campaign.

Still, Mr. Obama wants to hold his own against Mrs. Clinton in attracting big donors. He began assembling his bundlers well before announcing his bid in February 2007. Chairing his national finance committee was Penny Pritzker, heiress of Chicago's Hyatt hotel fortune. Running day-to-day fund raising was North Carolina native Julianna Smoot, who had raised money for the national trial lawyers association and Democratic Senatorial Campaign Committee.

Ms. Smoot put together a list of wealthy Democrats, and Mr. Obama, with only two years in Washington under his belt, deftly courted them.

Because Mrs. Clinton had enlisted many reliable party backers, Mr. Obama had to appeal to newcomers, said James Hudson, developer and Obama bundler. "It required some stretching," he said.

One major supporter is billionaire Neil Bluhm, a hotel and office building developer. But Mr. Bluhm has posed a symbolic problem for Mr. Obama in Pennsylvania because of plans to open a controversial casino along the Philadelphia waterfront.

In 2006, Pennsylvania awarded Mr. Bluhm one of two coveted Philadelphia gambling licenses. Last year, his partners in the project, called SugarHouse, were large donors to the Obama campaign.

Mr. Bluhm said that the gaming project "has got nothing to do with" his support for Mr. Obama and that the two have never discussed it. "My interest in him is, I think he's inspirational, I think he will enormously improve our economy and our relations with other countries," he said.

The Obama-Bluhm connection startled members of Philadelphia's anti-casino groups who knew that the senator had resisted efforts to legalize gambling. It was "really surprising to find [Mr. Bluhm] in Mr. Obama's corner," said Debbie King, who helped start Mothers Against SugarHouse. "I was inclined to vote for Hillary. But when I heard Mr. Obama's criticism about gambling, I thought about changing my vote. Now I'm not sure what to do."