Congressman Ron Paul has criticized front-runner Newt Gingrich, accusing him of "serial hypocrisy" and "selling access" in Washington.
Governor Rick Perry has not relented in his attack on Mitt Romney, who is running second in national GOP polls.
Cindy Rugeley, a political science professor at Texas Tech University, calls the campaign season leading up to tonight very interesting.
"It appears that the Republicans are trying to find some kind of alternative to Mitt Romney, but really haven't settled in on anybody that they really like. Right now, it appears that Newt Gingrich has a healthy surge. We'll just have to see what happens after the debate tonight and the caucus in a couple of weeks."
She says both Perry and Paul have a lot to gain with a good showing tonight.
"I think each of them have a different reason for what they're doing. For instance, Ron Paul, I mean he's going after Newt Gingrich, because I think that he sees that that's an area where he can pick up some voters. You look at Rick Perry. He's kind of saying, 'Well here's a way. It looks like Mitt Romney is vulnerable in Iowa, a caucus state, so if I can make a pretty decent showing there, show up above Mitt Romney, then I'm back in the race'."
Mark Jones, a political science professor at Rice University, says expect the candidates to go after Gingrich.
"He's a front runner, Ron Paul and Rick Perry already going very hard against him, Mitt Romney is as well. They have to walk a delicate balancing act though, in that they want to undermine Gingrich's credentials as a true conservative. But at the same time, they don't want to be seen by Iowa voters as overly negative."
Assuming he doesn't finish below fifth, Jones thinks Governor Perry will be sticking around for the South Carolina primaries the third week of January.