Mitt Romney's got a big problem in his fight with Rick Santorum: His supporters are a lot less enthusiastic, observes Nate Silver of the New York Times. According to one poll, Santorum is beating Romney by 11 points among people who are definitely going to vote. Romney leads by the same margin among indefinite voters, "but those votes don't count for anything unless the candidate can get the voters to the polls," something Romney hasn't been great at despite his cash advantage.
Instead of building field offices to drive turnout, Romney has fought the "air war," relying on advertising. But those ads have almost all been negative, and "negative ads are no way to increase your base," to grab those enthusiastic voters he so badly lacks. Going positive wouldn't guarantee a Michigan win, but would build a stronger foundation. "Already Mr. Romney's unfavorability ratings are reaching dangerously high levels," and unless he fixes that, "the party could be harmed in November even if he is the nominee." Click to read about Romney's op-ed in today's Detroit News. (Read more Mitt Romney stories.)