FAYETTEVILLE, Ark. - Lynn Giese calls Sarah Palin the best thing that's happened to the U.S. in a long time, and the 57-year-old housewife says she'd work tirelessly for the former Alaska governor were she to run for president in 2012.

"I'd do anything, go anywhere," said Giese, of Bokoshe, Oklahoma, while waiting in line at a Sam's Club in Fayetteville, where Palin signed copies of "Going Rogue," her best-selling memoir.

She'd also have support from Kayla Hogue, a 20-year old student who came to the same event sporting a button melding a photo of Palin and Ronald Reagan. And Bob Rutz, 78, first in line at Palin's book signing a day earlier in Springfield, Missouri, who said, "I'm hoping she'll be drafted (to run)."

These are the foot soldiers in Palin's army: thousands of devoted fans who show up to catch a glimpse of the one-time Republican vice-presidential nominee and former Alaska governor on her book tour and urge her to seek the nation's top job.

In Fayetteville, hundreds of people -- some camping out in frigid weather nearly a day before the event -- formed a line that snaked around the back of the store. They wore camouflage fatigues and suits, work boots and dress loafers, ball caps and cowboy hats and T-shirts that read, "Palintologist."

But while huge crowds greet her with roars of "Run Sarah Run!" as she tours the country in a bus, many national Republicans look on nervously, worrying the unparalleled enthusiasm she generates among some conservative voters isn't enough to power a Republican victory over President Barack Obama in 2012.

"People look at her and see themselves: patriotic, religious, family oriented outsiders looked down on by a liberal elite," said Jim Broussard, a political science professor at Lebanon Valley College in Pennsylvania. "But what makes her so attractive to her base makes her less attractive as an actual candidate, because you can't win with just your base."

In an increasingly urban multicultural country, the hordes coming out to see Palin are overwhelmingly white, conservative and from small towns (not surprisingly, since her book tour largely avoided cities.) They often express disdain for Obama, the mainstream media and the culture of Washington, which they said doesn't reflect them or their concerns.

"B.O. scares me," said Miki Booth, 59, of the president, adding that Palin "is as American as it gets."

Palin played into that fear on a radio show Thursday, telling host Rusty Humphries that voters "rightfully" have questions about the legitimacy of Obama's birth certificate. The so-called birther conspiracy around Obama's U.S. citizenship has been widely discredited, and state health officials in Hawaii have repeatedly confirmed that the president was born there in 1961. Obama's father, also named Barack Obama, was from Kenya.

Palin later backed off the comment on her Facebook page, saying she had never questioned the president's citizenship but believes that voters and reporters had a right to ask candidates whatever questions they wish.

Palin has not indicated whether she plans to run in 2012. But in a wide-open Republican field with no obvious front-runner, she is better known and excites much bigger crowds than others eyeing a run, including Minnesota Gov. Tim Pawlenty and former Massachusetts Gov. Mitt Romney.

Former Arkansas Gov. Mike Huckabee, a 2008 contender who might compete with Palin for the votes of social conservatives, saw his presidential prospects diminish this week after a man whose prison sentence Huckabee commuted nine years ago shot and killed four police officers in Washington state.

But Palin also has much higher negative ratings than her potential rivals, especially among Democrats and many independent voters. An ABC News/Washington Post poll taken in mid-November found 52 per cent of those surveyed had a negative opinion of her, compared to 43 per cent who viewed her positively.

Republican pollster John McLaughlin commended Palin's ability to "give voice to people who think the government doesn't care about them and really see Washington as disconnected and adversarial to their lives." But he warned that the negative impressions generated during her time as John McCain's 2008 running mate could prove a steep hurdle to overcome as a presidential contender.

"There are some inside the Republican Party who think she's too conservative and not up to the job," McLaughlin said.

Greg Mueller, a Republican strategist with deep ties to the conservative movement, acknowledged Palin's strongest ties were to the party's more rightward edge. But he noted that she also appealed to nonaligned voters more concerned about taxes and spending than conservative social issues -- the kind of voters who supported Ross Perot in the 1990s -- as well as women who thought she had been mistreated during the 2008 campaign.

"Her appeal is antiestablishment, populist, and to centre-right women finally seeing one of their own emerge only to be attacked and undermined," Mueller said. "It goes beyond presidential politics -- it's cultural."

Still, even some of Palin's stalwart supporters don't necessarily see her as a likely 2012 contender.

"Do I think she's presidential material? Um ..." said Sandy Adrian, at the Fayetteville book signing, pivoting one hand in a gesture of ambivalence, even though three copies of Palin's book were stacked in her shopping cart.

But, Adrian added, "you don't have to be president to change the world."