Rick Perry has been campaigning in South Carolina since the Iowa caucuses, looking for a game-changer.  He may have found one, but not in the nature he was seeking.  As a consequence of joining Newt Gingrich’s attack on Mitt Romney over his private-equity experience, one of Perry’s big donors has quit — and switched to Romney:

One of Rick Perry’s leading financial supporters in South Carolina is defecting to Mitt Romney – and he told CNN Thursday that Perry’s sharp criticisms of Romney as a “vulture capitalist” were the main factor in his decision. …

Barry Wynn, the former chairman of the South Carolina Republican Party and a financial adviser in Spartanburg, said the escalating rhetoric about Romney’s business background is “destructive.”

“It’s just a dance I didn’t want to be a part of,” Wynn said in an interview, explaining his decision to leave Perry’s campaign.

Wynn, along with a handful of other previously neutral South Carolina moneymen, will publicly endorse Romney on Thursday.

“This latest attack, it’s so foreign to me, I couldn’t see myself being a part of that,” he explained. “I don’t think you can be on both sides of free market capitalism. A big part of me being a Republican for the last 40 years is that I think it’s the best hope to protect free market capitalism, the growth engine of our economy.”

There could be some populist cred for Perry if big donors tied to Wall Street start leaving him, but that’s a big trade-off for the funding Perry desperately needs in South Carolina.  If he can’t put ads on the air and compete with Romney, Santorum, and Gingrich, then Perry won’t go anywhere in his last-gasp effort to stay in the race. He’s already at the bottom of the pack in the latest Insider Advantage poll, at 5%.  Even Jon Huntsman scores better than Perry in South Carolina, at 7%.

The defection of Wynn looks a like a more principled version of what happened to Michele Bachmann in the last few days of the Iowa campaign. It’s likely to produce the same effect for Perry in South Carolina as it did for Bachmann in Iowa, which is to create the impression of an imploding campaign.