By Jamie Coomarasamy
BBC News, Iowa
When Hillary Clinton's "Middle Class Express" campaign bus rolls into town, the townsfolk know it.
Hillary Clinton's campaign bus makes an impression in Iowa
While some presidential candidates are taking the traditional Iowa route, engaging in question-and-answer sessions in small halls or private homes, the New York Senator is taking a different one to - or, more accurately, back to - the White House.
In the town of Ames, her imposing blue bus parks just off Main Street, where a special stage has been constructed.
Two stages, in fact. On one, an all-female folk rock band called Raining Jane performs, as a warm-up act.
It is a far cry from the traditional, small-scale "retail politics" associated with campaigning in the state, which is traditionally the first to nominate its candidates.
After an introduction by a nervous seventh-grader, Mrs Clinton steps on to the main stage.
She delivers a confident, wide-ranging half-hour speech, in which she berates President George W Bush and praises former Presidents Eisenhower, Truman and - yes - Bill Clinton.
But there's only a fleeting mention of her fellow Democratic candidates ("you don't have to be against anybody, you only have to decide who you're for") and, on this stop at least, no questions from the crowd.
She is staying above the fray, running this primary campaign as if it were the general election.
It is not hard to see why. Not only is she raising the most money, but - in national opinion polls - Senator Clinton has a lead of more than 20 points over her nearest Democratic rival, Barack Obama.
His own formidable fundraising ability has not yet been translated into publicly-expressed support.
She is even leading in Iowa these days, having recently overtaken the former vice-presidential candidate, John Edwards.
The perception is growing that she is the inevitable nominee; a perception that has been reinforced by Republican candidates, relishing the prospect of a match-up against an opponent who would be a rallying point for their party's base.
Among those watching her in the town of Ames is the dean of the Iowa press corps, David Yepson, of the Des Moines Register. He has seen plenty of front-runners trip up.
"This notion that Hillary Clinton is the inevitable nominee hurts her in Iowa," he says.
"I've seen situations where a candidate gets more votes than anyone else, but is perceived as a loser because it wasn't good enough for somebody.
"This isn't a good position for a candidate to be in. It helps them raise money, but - this early in the race - it's a double-edged sword."
Which is what John Edwards is counting on.
On the same day that Mrs Clinton was speaking in Ames, he was appearing in the rather more modest Corydon Prairie Trails museum, in southern Iowa.
Against a backdrop of antique farming equipment, he takes questions from a rural, blue collar crowd, who seem largely supportive of his union ties.
Trailing in the national polls and fundraising stakes, Iowa is a make-or-break state for his campaign and - adopting a far more combative tone than that used, until now at least, by Mr Obama - he frequently criticises Mrs Clinton's policies.
In particular, he rounds on her recent vote in the Senate to designate the Iranian Revolutionary Guard a terrorist organisation; a vote which - he argues - could be used by Mr Bush as a pretext for war.
The former senator, who now says that his 2002 vote to authorise the war in Iraq was a mistake, uses a folksy adage: "Fool me once, shame on you, fool me twice, shame on me."
And he brushes off the importance of the "Clinton juggernaut".
"Four years ago, I lived through the inevitability of Howard Dean," he tells me. "And he didn't win a single primary or caucus.
"Voters will decide nearer the time, based on who has the best policies - and who is the most electable."
Further down the Democratic pack, but not giving up hope, either, is Bill Richardson.
He was in Iowa at the same time as his two rivals, holding what he called a "Job interview" and "Iraq Town Hall" tour.
The New Mexico governor, a former UN ambassador and US energy secretary, is arguing that he has more experience than the other candidates and a plan that would end the war in Iraq more swiftly than any of theirs.
In a meeting room in a nondescript, roadside hotel, he introduces himself to an audience of several dozen, and afterwards assures me that this remains the only way to win this crucial first state.
"This race will be decided by how many people in Iowa you touch and get to know personally," he insists.
"Iowans like to see their candidates. They don't like to see their candidates swoop in with thousands of security agents and then leave after an hour without taking questions."
But while the enthusiastic audiences in Iowa don't get to ask questions of Hillary Clinton, they do get to shake her hand and have their photograph taken with her, all under the watchful gaze of her secret service agents.
At the moment, the New York Senator has what the first President Bush once referred to as "the big mo": momentum. She has three long months, until the primaries, to maintain it.