But the Gingrich campaign has been quick to focus on Congressman Ron Paul's recent issues. Paul published newsletters in the 1980s and 90s that contained racist, anti-Semitic and anti-gay material. "These things are really nasty," said Gingrich. "And he didn't know about it? Wasn't aware about it and he's sufficiently ready to be president?"

Paul disavows the newsletters, saying he did not write them. But a YouTube video from 1995 shows a different stance. "It's called the Ron Paul survival report and I put that out on a monthly basis," he said in the video.

Still, Congressman Paul has passionate supporters who like his no-frills authenticity. Important in Iowa where slightly more than 100,000 people will vote.

The third top-tier candidate is former Massachusetts governor Mitt Romney, who has campaigned less in Iowa than some others. "The experience of balancing budgets is desperately needed in Washington and I will take it there," he said.

Romney touts his economic expertise in this new TV ad. But some staunch Republicans complain he's not conservative enough on other issues.

The good news for all three candidates is that Iowans have not chosen a clear favorite yet. The bad news is they have less than a week to become that favorite.