DES MOINES, Iowa -

Iowa Republicans go to their caucuses Tuesday night to talk it over and cast their ballots.

While six candidates are on the ballot, the polls show it could be a photo finish.

Three candidates have a shot at winning: former Massachusetts Governor Mitt Romney, former Pennsylvania Senator Rick Santorum and Houston area U.S. Rep. Ron Paul.

Earlier in the day at a town hall meeting in downtown Des Moines, Lt. Gov. David Dewhurst told KPRC Local 2 that Rick Perry is increasingly invigorated by each campaign stop in Iowa, unaffected by lackluster polls.

Dewhurst continued, "I'm very, very optimistic really. It depends on who turns out this evening and if enough people turn out, I'm very optimistic on the governor's chances."

Hoping to sway the undecided, candidates like Bachmann, Paul and Santorum stumped for votes at a huge Rock the Caucus event.

Senior Anna Brown told KPRC Local 2, "I honestly don't know at this point. I'm just trying to listen and learn a little more about what I want to do before I make any decisions."

In Iowa, it's all about the undecided vote. At Valley High School in West Des Moines, where Rock the Caucus was held, there are 600 students who are eligible to vote in the caucuses Tuesday night and any of those could change the way this caucus goes.

Carlyn LaGrone is the very definition of undecided.

She said, "I feel like I would vote for Ron Paul or Newt Gingrich. I don't really agree with a lot that Michelle Bachmann says as well as Rick Santorum. Actually, I'd vote for Mitt Romney. I change my mind."

Senior Bernie Saggau said the only thing he can predict is he'll probably change his mind at the last minute.

He explained, "I'm kind of siding with Ron Paul a little bit and Newt Gingrich even though they're kind of rivals against each other and I like Mitt Romney."

It's that indecision that has the GOP candidates barnstorming until the very last minute.

Several of them will actually make stops at precincts across the state to give voters one final nudge.