A week before Herman Cain’s announcement on Saturday to drop out of the presidential race, his Iowa campaign headquarters already exuded a telltale lack of buzz.

The few staffers occupying the low-slung building at the edge of a shopping center here on Tuesday had just heard their candidate announce on a conference call his plans to “reassess” his candidacy after yet another woman stepped forward with allegations of personal misconduct.

Campaign spokeswoman Lisa Lockwood leaned back at her neat desk under a whiteboard identifying her as the “Director of Fun and Secretary of Candy Distribution.” But Lockwood didn’t sound at all cheery as she compared Cain to a product that failed to catch on.

“If it doesn’t fly,” she said. “You are not going to keep selling it.”

The removal of Cain from the Iowa political market -- now made official -- has set off a post-Thanksgiving sales blitz by the leading candidates.

After months of discounting Iowa, the contenders are suddenly shopping their wares for the electoral season. This week, Mitt Romney aired his first Iowa TV ad, sent his son to rally supporters and announced that he had always cared about Iowa after all. Ron Paul planned two college rallies that promised to draw legions of the young supporters who constitute his electoral army. And both of them attacked Newt Gingrich, the field’s resurrected darling, who campaigned across the state.

There comes a point in every presidential cycle when the field thins and the surviving candidates scramble after the supporters. Now marks the beginning of the Iowa endgame.

‘Crunch time’

The Iowa caucus is served up daily at The Waveland Café, out on University Avenue. The waitresses pour coffee into mugs advertising C-Span, which, along with CNN, has turned the all-American-looking diner into a television studio in previous elections. The autographs of John Edwards, Ron Paul and Bill Richardson are scrawled directly on the walls.But this year, the staff lamented a drop-off in political activity.

“We had seen so many political candidates before,” said David Stone, the café’s owner as he pressed his palms on the counter Wednesday morning. “This time they seem to be here and gone very quickly. They speak at an event and then they are beating feet out of town as fast as they can go. My help is saying, ‘What is going on Stoney? There hasn’t been anybody.’ ”

But the collapse of Cain meant that the candidates had to start getting serious, Stone said. “It’s getting to be crunch time.”

No one seemed to agree more this week than Gingrich, who is looking to build on a surge in the polls after being left for damaged goods only months ago.

Not too far from The Waveland Café, across the city’s myriad strip malls and down a broad avenue lined with medical buildings, former member of Congress and plastic surgeon Greg Ganske swiveled on a stool in his clinic. Between an examination chair and black binders with labels like “Body Contouring,” Ganske recalled the “dark days” this summer when his old friend Gingrich crashed at his house to save campaign funds.

One night, Ganske said, he poured Gingrich a drink of Armenian cognac and watched as Gingrich wryly shook his head.

“ ‘This is probably the worst political start I’ve ever had,’ ” Ganske recalled Gingrich saying.

“The early stuff kind of inoculated him,” Ganske said. That included stories about Gingrich’s six-figure tab at Tiffany & Co. “The stuff about Newt’s bling seems inconsequential,” given Cain’s travails. In recent weeks, allegations of sexual harassment and an extramarital affair, combined with embarrassing brain freezes on basic foreign policy questions, have caused the businessman’s popularity to plummet.

Following Cain’s public reassessment, the Gingrich campaign announced that the candidate would be arriving in Iowa earlier than expected. He arrived on Wednesday evening at a “Slice the Deficit” Pizza Party at Pizza King (“Steaks, Chicken, Seafood, Cocktails”), a restaurant in the western town of Council Bluffs. In an interview there with the Post, Gingrich suggested that he never considered Cain or the other erstwhile front-runners in the Republican field threats.

“I always thought that would wear out,” he said, adding that “the only real decisive point” was when Texas Gov. Rick Perry entered the race. “I told my team, ‘If he can hit Major League pitching, the fact is we’ll never get past him.’ We didn’t have the weight at that time.”

Now that Gingrich has finally been called up to the Show, he is clearly delighting in the fact that Romney, who on Tuesday called him a “lifelong politician,” and, Paul who on Wednesday released a Web ad attacking him for shifting positions, feel the need to brush him back.

“Why would I want to be hit?” he said with a faint smile at the bar. “I’d be happier if they just relaxed.” Asked why he thought his rivals had begun to go after him, he replied, “They’ve got to do something.”

And why’s that, professor Gingrich?

“You look at the polls,” he said merrily, between sips of a diet soda. “And you tell me.”

Over the next two days, Gingrich took that new swagger and his un­or­tho­dox campaign style — part history buff, part McKinsey efficiency analyst, part “Newt.com” ad man — on the road, from the white windmills spinning lazily above grazing black cows in the west, across the khaki and fallow landscape to the hotel lobbies, corporate headquarters and Republican Party dinners around the capital.

At a convention of Iowa’s electrical co-ops in West Des Moines on Thursday, he gleefully said he didn’t know why no other candidates had shown up.

“I think this is a good place to be,” he remarked with an impish smile.

Romney’s scramble

The likely target of Gingrich’s jibe, Romney, has noticeably kept his distance, perhaps because his heavy investment in Iowa in 2004 didn’t yield. Instead, he is sending one of his sons.

“We’re having Governor Romney’s son Josh in the office tomorrow,” one young man pitched into a cellphone as he paced under “Romney Country” signs in the candidate’s newly opened headquarters on Tuesday evening. “It would be great if you could come out.”

The opening of the headquarters in an old Blockbuster Video building amounted to the first concrete sign that Romney had fully committed to winning here. This week, he announced that he would participate in two upcoming Iowa debates and dispatched one of his most popular surrogates, Gov. Chris Christie (R-N.J.), to Polk County.

“Romney has always said that he would campaign and compete in Iowa,” his spokeswoman Andrea Saul said in a statement.

Not everyone bought that line.

Some of the people who showed up at an event for Romney supporters demanded that the father come back to Iowa. And voters around the state expressed deep reservations about Romney as a “flip flopper.” For now at least, the candidate may reason that he has a better shot of winning over Iowans if he stays away from them.

Ron Paul has the opposite strategy.

“Being in Iowa as often as we have, the word gets out,” said James Barcia, the Paul campaign’s deputy Iowa state director. And as for poaching his voters, he said, don’t even think about it. “Our supporters are non-transferrable.”

Paul’s campaign has made a rigorous effort to expand its base from college kids to the larger, and older, voting universe. Recent surveys have shown that Paul’s operation had contacted the most voters of any candidate in Iowa.

“I’m embarrassed by that and will improve that,” Barcia deadpanned, as he sat at his desk dwarfed by a wall-sized map of Iowa.

As he later showed a reporter out of the office, Barcia hinted that the campaign would be making news later in the day. A few hours later, the campaign released a Web ad attacking Gingrich.

For now, though, voters seem to be interested in what Gingrich is selling.

Ed Daugherty, 68, of Council Bluffs, considered himself a Cain supporter before hearing Gingrich speak at the Pizza King. After the Gingrich speech on Wednesday night, he said that the candidate had impressed him more than Cain, Rick Santorum and Michele Bachmann, the only other candidates he had seen. “I’m leaning his way,” he said.

Daugherty and others then clustered around Gingrich as he shuffled out of the restaurant. They asked him to sign “Newt” stickers, some of the books he had authored and scraps of paper.

One woman, Jeanne Dietrich, handed him an edition of Time magazine from November 1998, the month he resigned as speaker of the House. The headline, over a stark and unhappy image of the speaker, read, “The Fall of Newt.”

Gingrich signed it. But for a rare moment this week, he did not look thrilled.