WASHINGTON -- Former Mississippi Gov. Haley Barbour (R) said Thursday he expects President Obama's reelection campaign and their allies to try to capitalize on Mitt Romney's lack of cash flow coming out of the Republican primary, and to try to overwhelm him with negative ads over the next few months.

"The time to really try to run down the Republican carpet bombing is about to start," Barbour said at a briefing with reporters at the National Press Club.

"If you got a bad record you want to try to disqualify your opponent to make him unacceptable," Barbour said. "And the easiest time to do it is this period when Romney doesn't have much money or access to much money, and they've got a huge amount of money that they haven't had to spend."

Obama's reelection campaign ended the month of March with $104 million in their war chest, compared to Romney's $10 million. Romney is expected to catch up to Obama in month-to-month totals, but has so far lagged behind the incumbent president because he had not clinched the GOP nomination and the party was not yet united behind him.

Romney has scheduled at least 20 finance events in at least 15 different cities over the next month, according to a fundraising schedule obtained this week by Politico's Maggie Haberman.

"Obama didn't have to run a primary so he's sitting on a stack of money so tall that a show dog couldn't jump over it," Barbour said, taking part in the briefing Thursday to review a series of focus groups with swing voters who voted for Obama in 2008. A Republican group, Resurgent Republic, conducted the focus groups.

Barbour, who left Mississippi office in January after two terms, now holds the title of honorary chairman with Resurgent Republic, and has also signed on with the Karl Rove-founded American Crossroads and Crossroads GPS groups. Those groups have said they intend to raise between $240 million and $300 million in this cycle, with about two-thirds of that total going to support the Republican presidential nominee and the other third going toward Senate and House races.

Barbour dodged a question about whether Crossroads will step in to defend Romney and give him cover as he hustles to catch up to Obama in terms of cash on hand. But his comments made clear that he is conscious of past Republican nominees who have been damaged in the lead up to the August conventions, and he would like to prevent that scenario from being repeated.

"Between that point and the convention, during the interregnum, [Bill] Clinton wore [Bob] Dole out during that period [in 1996]," Barbour said. "He spent about $150 million, if I remember right, on negative ads."

Crossroads and Crossroads GPS have raised $100 million so far. In addition, a super PAC supporting Romney, Restore Our Future, has raised about $51 million over the past 15 months. It spent most of its funds to get Romney through the contentious GOP primary, but is expected to continue raising money in large amounts given the ability of donors to give unlimited contributions to the group.

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