Former Alaska Gov. Sarah Palin has authorized a feature-length film about her rise, added staff and recently said she has "that fire in the belly" for a presidential bid _ all steps that fuel speculation she's inching toward a White House run.

Her supporters are putting together a campaign-in-waiting in Iowa, the lead-off nominating caucus, in the hopes the Republicans' 2008 vice presidential nominee decides to join the race.

There are even reports she bought a home in Arizona, not far from her daughter's, which aides have suggested could be a campaign headquarters if she goes forward.

Clearly Palin will be part of the conversation on Republican presidential contenders, but it's not certain she wants to be a candidate. With near-universal name recognition, loyal supporters and nearly unrivaled fundraising potential, Palin remains the biggest unknown in the presidential field and could wait longer than most to answer that question.

Palin is weighing her family's privacy against advice from a growing circle of political advisers. She rehired two former aides to help plan her events, suggesting she is ready to travel extensively again, and shuffled other advisers as she steps up her public appearances.

"I want to make sure that we have a candidate out there with tea party principles," she said recently.

That doesn't mean she's rushing to be that person.

Although Palin has made no obvious moves on her own behalf in early nominating states, California lawyer Peter Singleton has been meeting with county GOP organizations in Iowa since last winter. Working with Singleton, a group of Palin supporters has been building an independent, statewide organization this year at the ready should Palin decide to run.

"I don't know where Sarah's mind is, I don't think anyone knows that," said Meg Stapleton, who served as Palin's spokeswoman in the governor's office and after. "I think at this point in time, it's only within her heart and her mind and she's keeping it that way."

The GOP field is starting to set, with candidates making official their White House plans in recent or coming weeks. None, however, has truly engaged the party's base, and polls indicate likely primary voters and caucus-goers are dissatisfied and looking for other options. Should she run, Palin could fill that hunger and quickly galvanize a party eager to campaign against President Barack Obama but uncertain who their best warrior would be.

"I do have that fire in the belly," Palin told Fox News Channel.

She hasn't signaled how long that fire might burn, however. Palin's star power means she might not have to enter the race as early as the others. A late entry could build excitement for her, an online fundraising burst could quickly pay for the campaign and her social media prowess could trump a traditional campaign.

Palin also would come to the 2012 campaign with serious hurdles. She has a loyal following among conservatives and tea-party activists, but she remains a divisive figure among the wider public. Polls show more people have an unfavorable opinion of her than not, and her abrupt resignation from the governor's office two years ago is the open question for many Republicans.

Palin supporters hope an upcoming documentary about her rise and time as Alaska's governor will calm their worries. "The Undefeated," set to premiere next month in Iowa, is stoking speculation she wants to reframe how that period is characterized.

"This film is a call to action for a campaign like 1976: Reagan vs. the establishment. Let's have a good old-fashioned brouhaha," Stephen Bannon, the filmmaker, said in a statement.

Palin asked an aide to reach out to Bannon about making videos on her time as Alaska's governor; Bannon wound up making a movie instead, reported on the website Real Clear Politics, which broke the news of the film.

Stapleton, the former spokesperson, said she has seen a rough cut, which she said married interviews with Palin insiders with media accounts from that time to provide an "accurate portrayal of her record."

News of the film comes as a former member of Palin's inner circle published a scathing tell-all. Frank Bailey's "Blind Allegiance to Sarah Palin: A Memoir of Our Tumultuous Years" was based on tens of thousands of emails he collected. In it, he paints an unflattering portrait of Palin as someone who wanted to quit the governorship even earlier than her surprise resignation on the July 4, 2009, holiday weekend.

It also comes amid reports that the family purchased a $1.7 million home in Scottsdale, Ariz., where advisers have suggested a campaign could be based. Alaska's distance from the lower 48 states would be a major hurdle should she run, and trips to New Hampshire would consume entire days if she wanted to get home to spend time with one of her five children.

Scottsdale is an hour's drive from Maricopa, where Palin's 20-year-old daughter, Bristol, purchased a home.

Palin advisers would not comment on the Arizona properties. The New York Times, citing two people familiar with the details of the real estate transaction, said the Palins used a shell company that hid their identity.

It's not clear, though, whether the Republicans' 2008 vice presidential nominee, will ultimately decide to join the race. She commands six-figure sums for her speeches, earns a paycheck as a Fox News Channel contributor and is a best-selling author.

Should she run, she'd have to give up that income. Should she lose the primary, she'd give up some of her cache. And it's not as if she lacks for attention right now.

Whereas other potential candidates struggle for the limelight, Palin fires off 140-character missives on Twitter to her more than 525,000 followers. Her Facebook page offers her more serious opinions on the day's news to her almost 3 million supporters.

Ivan Moore, a pollster based in Anchorage, thinks Palin will run _ but for the notoriety, not the job.

"She's achieved what she's achieved in terms of earning money so far based on a failed vice presidential run," said Moore, who works for Republicans and Democrats alike. "Imagine what she could do from a presidential run."

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Elliott reported from Washington. Associated Press writer Thomas Beaumont in Des Moines, Iowa, contributed to this report.