She isn't the only convert. A McClatchy computer analysis, incomplete due to the difficulty matching data from various campaign finance reports, found that hundreds of people who gave at least $200 to Bush's 2004 campaign have donated to Obama.
"There is a large block of Republicans, particularly economic conservatives, who just feel that the Republican Party in Washington completely let them down" by failing to control spending and address other problems, Corrado said. "The Republicans have really given these donors no reason to give."
Larson said he's "not anti-Iraq war," but he said that Bush promised to bring people together when he ran for president and has failed to do so, while Obama has demonstrated in his campaign "that he has the ability to connect in ways that no other candidate can."
While they represent a tiny slice of Bush's 2004 donors, he said, a shift of longtime Republicans committed enough to write checks reflects "a real strain" in the GOP.
Calls to more than a dozen of the Bush-turned-Obama backers suggest there are multiple motives for their shifts.
Katherine Merck, 84, of Lexington, Mass., preferred not to recall her donations of $2,000 to Bush in 1999 and $2,000 in 2004.
"I just can't get over it that my name is in there for sending money to that miserable president," she said. "I think Obama is something we all need badly, really badly. I think that people need to grow up more and learn how to get on in the world without resorting to killing people. I'm talking about the war in Iraq."
"Am I all the way liberal?" Beverly Fanning asked. "I think I'm actually a conservative liberal. . . . It's not that I'm against McCain. It's just that Barack is my choice."
Worried about the loss of manufacturing jobs to Third World countries, she said, she began volunteering early this year for Obama, who says he'd consider amending trade pacts to protect those jobs.
Fanning said that her husband Tom, the chief operating officer of the Southern Co., a major electric utility, is a solid Republican who backs McCain for president but gave $1,000 to Obama in February.
"I told him, 'I have been volunteering for Barack Obama for five months,' " she said. "I thought the guy was gonna faint."
Some converts declined to give any hint of their reasons.
"I consider that to be a private matter," said Jeffrey Leiden, a Glencoe, Ill., cardiologist who's a former president of Abbott Laboratories' pharmaceutical products group.
Corrado said he thinks some of the ex-Bush donors have given to Obama to hurt Hillary Clinton — a suspicion confirmed by Henry Corey, 86, of Bronxville, N.Y., a longtime GOP donor.
He said he gave Obama $250 because, "frankly, I wanted to be sure that someone nudged Hillary Clinton aside. I think she'd be a disaster."
Chris Adams and Tish Wells contributed to this article.
McClatchy Newspapers 2008