The campaign has cycled through several front-runners and with just days left, the Iowa race is as unpredictable as ever.
First, Texas Gov. Rick Perry released a new ad accusing many of the other candidates of being Washington insiders.
"That's the reason I've called for a part-time Congress," said the political advertisement.
But Romney is increasing his efforts in Iowa, phoning supporters and releasing a new ad: "I'm going to do something to government. I'm going to make it simpler and smaller and smarter."
Romney will begin Tuesday in New Hampshire, and then head to Iowa where he will launch his bus tour on Wednesday.
Long-shot Rick Santorum spent the day after Christmas hunting in Adel, Iowa, and has picked up support from Christian conservatives in the state. He's now looking for an upset.
"I think we're doing pretty good," said Santorum.
But the candidate with apparently the most momentum right now is Texas Rep. Ron Paul, though he's facing questions about a controversial newsletter which contained anti-Semitic and anti-gay comments.
"I didn't write it and I disavowed those messages, or whatever was written," said Paul. "That has been 20 years ago and it has been rehashed many, many times."
The latest national Gallup poll shows Gingrich on top with 26 percent, and Romney close behind with 23 percent.
In New Hampshire, which votes one week after Iowa, Romney has a commanding lead with 39 percent, with Gingrich and Paul tied for second with 17 percent.
Polls show many of those expected to participate in next Tuesday's Iowa caucuses remain undecided and a majority is open to changing their minds.