Peebles said there are “constant phone calls and discussions” among finance committee members — including a Monday call in which he did not participate — urging bundlers to pick up the pace. “Trying to find new big donors, that’s one of the big things,” he said.

The problem, he said, is that Obama is alienating potential big donors with attacks on Wall Street while his reelection campaign has already reaped the maximum contributions from its most supportive big donors. So the challenge for Obama bundlers is identifying and courting new donors “because the donors who are predisposed to give to him have already given,” Peebles added.

But some Democrats are concerned that the presidential cash race may have reached a tipping point. While GOP super PACs have been outraising their Democratic counterparts for months, Democrats have taken solace in Obama’s ability to bring in heaps more campaign cash.