DES MOINES - The last Michele Bachmann saw of her Iowa campaign chairman, Kent Sorenson was standing by quietly in a Pizza Ranch restaurant in Indianola, where her "99-county" bus tour had stopped for a brief rally on Wednesday afternoon.

Asked to say a few words on Bachmann's behalf, the state senator mumbled something about dental work. "I'm numb," he told a few dozen supporters and onlookers. "I'm afraid I'll start drooling."

Hours later, Sorenson turned up at a Ron Paul rally in Des Moines, where he found his voice and completed his defection. "We're going to take Ron Paul all the way to the White House," he told a much-larger crowd cheering for the rival Texas congressman.

With just a few days left before Tuesday's make-or-break Iowa caucuses, Sorenson's switch marks the low point in an increasingly desperate presidential campaign, with Bachmann scrambling to stay relevant -- and on time.

It's also another sign of just how far she seems to have fallen since she campaigned to big crowds as Iowa's native daughter and won the straw poll in Ames at the end of the summer.

Now last in some polls and short on the cash needed to compete on the airwaves with the top-tier GOP candidates, the Minnesota Republican has just ended a punishing 10-day tour taking her to every county in Iowa, often hitting cafés and restaurants so fast she hardly had time to take off her coat. "We're the hardest-working campaign on the ground," Bachmann told supporters at the Northside Cafe in Winterset, in the heart of Madison County. "What we're seeing on the ground is nothing short of phenomenal."

But some GOP operatives say it's too little too late. And Sorenson's departure -- followed by Bachmann's accusation that he sold her out -- has contributed to the impression of a national campaign in disarray and losing ground in the very state where she has staked everything: her native Iowa.

"He was with me at our campaign stop in Indianola," Bachmann complained to reporters after a Thursday morning radio interview in Des Moines. "He told all of our campaign that he was definitely on board, and then he got in his car and went and announced that he was going with the Ron Paul campaign."

Bachmann fanned the controversy by calling it a "financial decision," alleging that Sorenson had told her the Paul campaign had offered him "a lot of money" and that he needed to "provide for his family."

Sorenson denied the charge. Appearing on Fox News on Thursday, he said "that conversation did not happen" and that he was "never offered a nickel."

The internal cracking continued, with Bachmann's political director, Wes Enos, weighing in with a statement through the Paul campaign that Sorenson's decision was "in no way financially motivated." Enos said he still supports Bachmann, although he quit her campaign later in the day.

'Running ragged'

Following the exodus of Bachmann's New Hampshire campaign staff in October, Sorenson's exit will inevitably raise questions about Bachmann's ability to mount a national campaign, especially one founded on conservative principles promising voters "no surprises."

Even before Sorenson bolted from Bachmann's camp, there were signs of strain on the campaign trail.

At a rally at Elly's Tea and Coffee House in Muscatine last week, Iowa GOP operative Craig Robinson said he encountered a crowd of about 50 eager Bachmann supporters. Robinson, editor of the Iowa Republican, thought it was a good crowd for a weekday morning, a perfect example of the sort of grass-roots politicking that might help Bachmann recoup some of the faded luster of her victory in the Ames Straw Poll in August.

The only problem: Bachmann wasn't there yet.

"There was a pretty vocal woman sitting next to me complaining that she's late," Robinson recalled. "I think the issue is that Bachmann was 50 minutes late, and then she spent a total of 12 minutes there."

Part of Bachmann's time in the café, Robinson said, was spent shooting a caucus training video, an exercise she has repeated in all 99 counties, averaging some 10 counties a day.

By the time she got to Muscatine, Robinson said, Bachmann was so hoarse that her voice was reduced to a whisper. "I actually think that instead of making progress for her campaign, she's just running herself ragged," he said.

In a campaign season shaped by a long series of nationally televised debates, some Iowans are starting to question Bachmann's heavy reliance on traditional retail-style politicking. Mitt Romney and Newt Gingrich have spent comparatively little time in Iowa until now. Meanwhile, Bachmann and fellow Christian conservative Rick Santorum, the only two to visit all 99 counties, have struggled to gain traction -- although Santorum is showing signs of a late surge.

Where the debates left off before the Christmas lull, the air space in Iowa is now filling up with political ads, the majority of them on behalf of the best-funded candidates: Paul, Romney and Texas Gov. Rick Perry.

Given the heavy emphasis on TV ads and the debates, University of Northern Iowa political scientist Christopher Larimer said, "There's a real concern in Iowa that the strategy is changing."

But with polls showing that more than half of potential caucus-goers have yet to make up their minds, Bachmann is holding out hope. "A lot of people are going to be shocked on Jan. 3," she said in Winterset.

'Vote waiting to happen'

Despite some turmoil at the top of her campaign organization, Bachmann boasts a well-developed ground game, with organizers signed up in every county in Iowa. "It's a mistake to say the debates have supplanted caucus organization," said Tim Albrecht, an unaffiliated GOP operative and aide to Gov. Terry Branstad. "There's a real opportunity for those candidates who are out there, who are traveling the state."

Still, Albrecht sees an uphill battle for Bachmann, partly because her target audience of evangelical social conservatives is split among Santorum, Perry and her. Some evangelical leaders have called for her to leave the race or join forces with Santorum or Perry.

"What we're seeing is a lot of these conservatives are fragmenting their support," said Bob Vander Plaats, a Santorum supporter who heads the Family Leader, a faith-oriented group that remains technically neutral in the race.

The state's Tea Party activists also have been split, with Sorenson providing fresh evidence of the movement's divided loyalties.

Among those who have stuck with Bachmann is Tea Party of America co-founder Ken Crow, now Bachmann's Madison County chairman. He, like the rest of her top cadre of advisers, believes that in Iowa face time trumps money, like it did for former Arkansas Gov. Mike Huckabee, who won the state's GOP caucuses four years ago. "Romney spent millions," Crow recalled. "And he got his backside whipped in Iowa by a pastor from Arkansas who did all the coffee shops and county fairs."

Madison County was Bachmann's 94th stop on her Iowa tour. There she met Stacy Billeter, a granite countertop man whose family owns the Northside Cafe. Terming himself undecided, he told Bachmann, "I'm just a vote waiting to happen."

Her pitch to Billeter: "I need your vote because I'm real."

She got it, he said.

It was just after sundown. Sorenson was on his way to rally with Ron Paul.

Kevin Diaz is a correspondent in the Star Tribune Washington Bureau.