The line on the Iowa caucuses: Romney has best odds, Santorum has the momentum At this point, there's not much left for the candidates - or the reporters who cover them - to do but wait and wonder. Now, the Fix isn't a betting man, but there is no better way to wile away the hours between now and Tuesday night than to do a bit of odds-setting. Below are the odds we give each candidate in Iowa. The numbers are based on conversations with strategists for many of the contenders, independent poll figures and a little bit of historical context sprinkled in for taste. Mitt Romney (2-1): The former Massachusetts governor is the best bet to win the caucuses because he is the only candidate aggressively competing for the mainstream/establishment vote in the state. The five others in the race are trying to emerge as the social-conservative/tea party choice. Although more social conservatives than mainstream Republicans participate in the caucuses, the fracturing of the evangelical vote means that Romney's 25 percent could be enough (or close to enough) to win the nomination. He received 25 percent in the Iowa caucuses in 2008 and lost to former Arkansas governor Mike Huckabee by nine points. Romney and his team know that a victory in Iowa followed by another in New Hampshire would all but lock up the nomination for him, so he is pushing - hard. Rick Santorum (6-1): A Des Moines Register poll released Saturday night made plain that the former senator from Pennsylvania is the momentum candidate. Although he took 15 percent overall in the four-day survey, he was at 21 percent in the final two days - a sign that he is peaking in the waning moments. The key for Santorum is how much of the vote he can peel off other socially conservative candidates - most notably Texas Gov. Rick Perry, who, despite major spending in Iowa, doesn't appear to be rising fast enough. Ron Paul (7-1): The congressman from Texas has the most reliable base - between 15 percent and 19 percent - in the field. But his ability to grow beyond that has always been very much up in the air, and it's even more so now as Paul has come under withering attack from the likes of former House speaker Newt Gingrich (Ga.) and Rep. Michele Bachmann (Minn.). Both Bachmann and Gingrich have painted Paul not only as outside the mainstream of Republican Party thought, which he is, but also as potentially dangerous if elected. Although conventional wisdom holds that if turnout in the caucuses is low (less than 100,000) it's good for Paul, there's also a case to be made that high turnout (120,000 or more) might be even better. The more nontraditional Republicans who decide to vote Tuesday (Iowa has same-day registration), the better for Paul. Newt Gingrich (20-1): If the caucuses had been held Dec. 3, Gingrich would have won. But his baffling pledge not to go negative combined with his inability to raise enough money to compete with his rivals (and their affiliated super PACs) on television doomed his chances over the past month. Gingrich has insisted that South Carolina is where he will make his stand, but if he finishes outside of the top three in Iowa it might be hard for him to raise more money and stay viable through the Palmetto State's Jan. 21 primary. Rick Perry (25-1): The Texas governor's inability to gain any real traction despite outspending all of his rivals in the Hawkeye State reveals just how damaging his disastrous debate performances were late last year. Although Perry is, at best, a socially conservative spoiler for the likes of Santorum at this point, he will almost certainly be remembered as a "what might have been" candidate. His profile - and ability to raise money - should have made him Romney's main competition nationally and the front-runner in Iowa. Instead, he'll be the latest reminder that candidates and the campaigns they run matter. Michele Bachmann (50-1): Need a sign of how fluid this race has been? The congresswoman from Minnesota was the Iowa front-runner when she won the Ames Straw Poll in mid-August. A little more than four months later, she is the heavy favorite to finish last in the caucuses. Bachmann's inability to raise money has badly hamstrung her, and she has been a shadowy presence on Iowa airwaves over the past month. If she does come in sixth Tuesday night, it's hard to imagine her staying in the race through the Jan. 10 New Hampshire primary.