John McCain, on the other hand, continues to see his fund raising surge. He took in $250,000 over the Internet in the 24 hours after winning GOP primaries Tuesday in Arizona and Michigan.

Bush already has collected the maximum $1,000 from 48,458 people -- almost as much as all the Republican presidential candidates combined in the last election, according to the Center for Responsive Politics, a nonprofit research that studies money and campaigns. There were 48,786 people who gave $1,000 to GOP presidential candidates in 1996.

Because contributors can't give more than $1,000, Bush must find new donors, and he plans some big-ticket fund-raisers next month to do just that.

But experts caution that the search for additional contributors may get more difficult because Bush's aura of invincibility has been shattered by his string of losses.

"He has a spotty record, to say the least," said Herbert Alexander, professor emeritus of political science at the University of Southern California. "It's not certain that he's a winner and under those circumstances, it's not certain as to why people might want to give to him at this late date. There's absolutely no question that it will be harder to find as many new contributors as he already has."

Bush may find support among some of the 85,000 people who gave at least $1,000 to the Republican Party or a GOP congressional candidate in 1996 but skipped the presidential race, according to the research center. Alexander suggested Bush also might find fertile ground for new donors among the spouses of people who already gave or among recent Internet millionaires, who are just now beginning to contribute to political campaigns.

In contrast, McCain has raised half of his money in contributions of less than $1,000. That means he can ask the same donors to give again because they have not reached the legal limit.

McCain also has experienced a windfall on the Internet, where he has raised more than $5 million. Since most of that money came in contributions of less than $250, it is eligible to be matched by the federal government. Bush is not accepting federal funds.

McCain now has $9 million to spend, including future federal funds. Though Bush had $20 million in the bank at the start of February, he has been spending at the rate of more than $3 million a week and raised just $1.5 million through Feb. 16. His campaign balance is below $15 million.

Bush's biggest advantage may be that he already has spent millions in states holding primaries through March 14, when the nomination likely will be decided. He is on the air in California, North Dakota, Virginia and Washington state. McCain, meanwhile, reported spending just $93,021 in California thru Jan. 31.

Bush spokesman Scott McClellan said Bush is confident he'll be able to raise money.

"We always said it would be a competitive primary," McClellan said. "We built strong, broad based support early in order to maximize our resources toward voter contact in the early primary states. We're continuing to build on that support."