Mitt Romney won yesterday’s two primaries in Arizona and Michigan, but he didn’t win by enough to (re)establish a sense of inevitability around his candidacy. He has been the favourite for so long that everything but decisive victories ends up being framed as a bit of a disappointment. Here is Whit Ayres, a Republican political operative, speaking to the Washington Post a few days before this week’s primaries—“if [Romney] wins Michigan by double digits, especially if combined with a double-digit Arizona win, then all the chatter will die down just like it did after Florida.” But Romney didn’t win Michigan by double-digits, and the chatter hasn’t died down. Though Santorum lost both states, no one seems to really hold it …