Candidates Roll Across Iowa [VIDEO]

Three Republican presidential candidates, each claiming to be the truly conservative alternative to Mitt Romney, are launching bus tours Tuesday through this early nominating state.

Just a week before Iowa's leadoff caucuses, Minnesota Rep.Michele Bachmann, Texas Gov. Rick Perry and former House Speaker Newt Gingrich prepared to rumble through small towns aboard their campaign buses. They're looking for supporters one at a time and hoping to become a roadblock for Romney, who is looking stronger than expected. Romney returns to Iowa on Tuesday after a quick stop in his long-established stronghold of New Hampshire.

Ahead of the Jan. 3 caucuses that officially begin the GOP's nominating calendar, the candidates were returning for a final rush of speeches, meet-and-greet stops and town hall-style meetings. And they are bracing for one last round of advertising, which most observers are expecting to be nasty.

Each campaign has also tried to gauge the level of enthusiasm for Rep. Ron Paul of Texas. The libertarian favorite has built a strong organization here and recent polls suggest he is peaking, a rise that has him tied with or even ahead of Romney -- and drawing more scrutiny for his views.

"There's really three primaries going on here," former Sen. Rick Santorum of Pennsylvania told reporters in Adel, where he went hunting for pheasant and quail. "There's the libertarian primary, which Ron Paul is going to win. Then you've got the moderateprimary, which Gingrich and Romney are scrumming for. And you've got three folks who are running as strong conservatives."

(Copyright 2011 by The Associated Press.  All Rights Reserved.)