Washington DC, May 19: Pivoting toward the general election, Senator Barack Obama is turning again to his history-making fund-raising machine, which helped to anoint him as a contender against Senator Hillary Rodham Clinton and then became a potent weapon in their battle for the Democratic nomination.

To confront the Obama juggernaut, Senator John McCain, whose fund-raising has badly trailed that of his Democratic counterparts, is leaning on the Republican National Committee. McCain’s efforts to raise money suffered a blow this weekend when a key fund-raiser, Tom Loeffler, resigned because of a new campaign policy on conflicts of interest.

McCain is likely to depend upon the party, which finished April with an impressive $40 million in the bank and has significantly higher contribution limits, to an unprecedented degree to power his campaign, Republican officials said.

To that end, Republican officials said they were enlisting President Bush, a formidable fund-raiser who has raised more than $36 million this year for Republican candidates and committees, for three events on McCain’s behalf. They will appear together at a fund-raiser in Phoenix on May 27, and the next day the president will take part in a luncheon with Mitt Romney in Salt Lake City and then an exclusive dinner at Romney’s vacation home in Park City, Utah.

McCain, who abandoned public financing in the primary but has indicated he would employ it in the general election, is aggressively building a joint fund-raising operation with the Republican National Committee and state party committees in four battleground states. These committees can raise money far in excess of the $2,300 limit imposed on individuals giving to McCain’s presidential campaign. Donors can write a single check of almost $70,000 to the committees that is divided up to various entities.

Offering a glimpse of the kind of money that can be spread around with such a committee, $300,000 was collected from nine hedge fund executives and real estate investors at an event in New York in March, according to a report filed with the Federal Election Commission. More than $10 million was raised at an event on Thursday in Washington, McCain campaign advisers said. Lacking a robust small-dollar Internet fund-raising operation, McCain has a busy schedule of some two dozen high-dollar fund-raising events this month.

McCain’s advisers say they hope their joint fund-raising efforts can raise $150 million, or just over $20 million a month until November. Coupled with the $84 million McCain would receive through public financing, which the campaign could spend in the two months after the Republican convention, his advisers insist they will have enough resources to compete with Obama.

The Republican National Committee raised roughly $20 million in April, said Mike Duncan, the committee’s chairman. McCain collected $18 million in April, his second full month as the presumptive Republican nominee, a campaign spokeswoman said.

Running a lean campaign, however, and shifting many functions to the national committee, McCain has amassed a war chest that left him more than $21 million in the bank at the end of April.

But McCain’s heavy reliance on the party comes with limitations. Only a relatively small pool of money can be used in advertising that is coordinated between the party and the campaign. The party can also share the costs for generic advertisements .