WASHINGTON — Since former Alaska Gov. Sarah Palin shot to fame after her 2008 vice presidential bid, she's kept her intentions — if not her ambitions — closely held.

But on Thursday, Palin's ambitions began to look increasingly presidential. Her political action committee announced that she'd launch a multi-state tour over the Memorial Day weekend, beginning at a motorcycle rally in Washington and winding its way up the East Coast to New Hampshire, the site of the nation's first presidential primary.

"I've said many times that America doesn't need a 'fundamental transformation,' " Palin said in an announcement on her website. "Instead we need a restoration of all that is good and strong and free in America! So, together let's prepare ourselves for the days ahead by reminding ourselves who we are and what Americans stand for."

Palin still hasn't officially announced a candidacy, but the evidence piled up this week. She told Fox News Channel that she had "fire in the belly" for a presidential bid. Her closest advisers confirmed that "The Undefeated," a flattering documentary by conservative filmmaker Stephen Bannon, would premiere next month in Iowa, the site of caucuses that are the nation's first presidential contest. She and her husband, Todd, even reportedly bought a house in Arizona, to have a more accessible home base in the Lower 48.

And although Palin has said that filing deadlines, family considerations and the other aspiring officeholders in the field would shape her ultimate decision, the blue bus emblazoned with the motto "One Nation" left little question that the upcoming tour is but a precursor to a full campaign.

Palin's potential candidacy has been the biggest open question as the Republican presidential primary field has solidified in recent weeks. Her biggest potential rival on the far right, former Arkansas Gov. Mike Huckabee, announced that he was out; meanwhile, former Minnesota Gov. Tim Pawlenty and former House Speaker Newt Gingrich announced that they're in.

Others who haven't made official announcements, such as 2008 contender and former Massachusetts Gov. Mitt Romney and Rep. Michele Bachmann of Minnesota, already are spending plenty of time in key primary states: Iowa, New Hampshire and South Carolina.

"By and large, they know where she stands on a lot of issues," said Iowa's Steve Scheffler, a GOP national committeeman, who hasn't endorsed anyone. He's also the president of the conservative Iowa Faith & Freedom Coalition.

"But I think Iowans rightfully expect their candidate to be vetted well, in small groups and one on one," he said. "If she's going to run, they'd very much like her to come here sooner rather than later."

Former Pennsylvania Sen. Rick Santorum has been to New Hampshire at least 15 times already, said Jennifer Horn, the president of We the People, a conservative group.

"If she's serious about running, she has to get here," Horn said. "She doesn't have to make up ground so that people know who she is. She has to make it clear that she's serious about running. You've got to be up here and you've got to be playing on a regular basis. We expect personal commitment."

Palin's loose organization — she hired a chief of staff only recently — has led many establishment Republican figures to question whether she had enough people with the command of the logistics necessary to pull off a presidential bid. But that lack of a formal organization belies one of her greatest strengths, said one longtime observer from Alaska, Democratic pollster Ivan Moore.