Is The Horserace Effectively Over?

Douthat thinks so:

While there are still scenarios in which the frontrunner ends up 50-100 delegates short of the magic number at the end of primary season, it would take a truly extraordinary turn of events (a huge scandal, say) to deny Romney the nomination at this point. The chaos-at-the-convention scenarios were almost plausible pre-Michigan, but they only made sense in a world where the leading candidate ended up well short of the necessary delegates. Now Romney is on track to win at least a clear plurality, and if he goes to the convention with over a thousand delegates, Jeb Bush isn’t going to sweep in and swipe the nomination out from under the man who won the most primary-season votes. It just … isn’t … going … to happen.