The four remaining Republican presidential candidates will be debating tonight at 5 pm on CNN. This could be the final Republican debate—they've already canceled the March 1st debate in Atlanta, and I'm not very hopeful for the prospects of the March 19th debate scheduled here in Portland.

Tonight's debate could be a game-changer. Arizona and Michigan are voting next Tuesday, and the race is tightening up. I think Santorum is losing support; the newest poll shows Romney with a slight edge in Michigan. If Santorum is following the traditional Republican frontrunner cycle—leap to first place, talk a whole lot, scare off voters—he could be at the very top of a steep downward slope. This debate could be his only opportunity to sound sane and presidential to a large group of voters. Meanwhile, Romney needs to reassure voters that he's a real conservative after yesterday's outburst of sanity, Gingrich needs to give his best debate performance yet, and Ron Paul? He can just keep being Ron Paul.