With the field clarifying, Mitt Romney’s interests now align well with those of one other possible candidate: Michele Bachmann. Both of them have an interest in seeing her do as well as possible. Like Bob Dole in 1996 or John McCain in 2008, Romney is an establishment-oriented candidate with serious vulnerabilities on his right flank. To get the nomination, he needs (as they needed) to prevent the emergence of a single candidate to his right. So Dole made a tactical alliance with Pat Buchanan in Lousiana, helping to eject from the race the one candidate who could theoretically have denied...