(note: sorry about the horse-race post)
Tomorrow, Michigan and Arizona have their primaries. The polling in each state indicates a likely Romney win in Arizona and a close finish in Romney's home state of Michigan. With these expectations set, Arizona won't matter in terms of bounce and/or impact on other races. Michigan, however, has a chance to have huge influence over the remainder of the primary season. There are two possible outcomes:
1. Romney wins, even narrowly. This blunts Santorum's momentum and gives Romney a bounce into Super Tuesday, one week later on March 6. He'll probably lose Georgia (to Gingrich), Tennessee and Oklahoma (to Santorum) regardless, but a win in Michigan will give him a decent shot at Ohio, along with likely wins in Massachusetts, Virginia and Vermont. and he'd probably be able to hold off Ron Paul in the caucuses in Idaho, Alaska, Wyoming and North Dakota. He re-establishes himself as the inevitable nominee. Like Obama in '08, he'd have a long primary season before he'd finally vanquish his foes, but with the eventual nomination in hand, he can kind of float above the fray, using the free media of the ongoing primary to rehabilitate his image and lay off the harshest attacks on his opponents.
2. Santorum beats Romney in Mitt's home state, where his father was a popular governor. Romney's aura of electability/inevitability is destroyed forever. He goes on to lose Ohio next week. Conservatives in Virginia, where only Romney and Paul are on the ballot, line up behind Paul to deny Romney a win. He finishes third in Georgia, Oklahoma and Tennessee and loses a couple caucus states to Paul. The race is blown wide open, and we don't know the name of the nominee until the convention in August.
So it'll be a big night. I still think Romney wins both states tomorrow and will be the eventual nominee, but I'm not nearly as confident now as I was in November.