This is the opening paragraph, which also contains Beinart's thesis:
According to the old rules of American politics, Mitt Romney should win the Republican presidential nomination. He came in second last time. He’s got lots of money. He’s got a better chance of defeating Barack Obama than his leading opponents. But he’s unlikely to win because we live in an age of presidential hatred. These days, to win your party’s nomination you must be the polar opposite of the president your party despises. Any significant resemblance between yourself and him and you’re done.I think this is an over-analysis. Mitt Romney is currently running second in the Republican primaries for two reasons. First, he is to the left of the Republican primary electorate, which is being dominated by members of the Tea Party and they are extremely conservative. Second, right now President Obama looks quite weak, which is leading voters in the Republican primary to prioritize ideological purity over electability. If Perry implodes or if Romney moves more to the right to match the ideological distribution of the Republican electorate, or if the President regains his footing Romney is likely to win the Republican Primary.
Sometimes the simple explanation is probably the right one. Perry, the former Democrat, is more conservative than Romney; he is more ideologically aligned with the Republican electorate, which is why he has taken all the winds out of out Michele Bachmann's sails. It is that simple.