For Romney, the new alignment offers one clear advantage: the possibility that the voters least likely to support him will be splintered between two opponents rather than consolidating behind one. Both in his 2008 bid, and in early 2012 polling, Romney has run best with voters holding at least a four-year college degree and those who do not identify as evangelical Christians -- what might be called the party's managerial wing. Romney has always struggled with the party's populist wing, composed mostly of evangelical Christians and Republicans without a college degree.
The Republican coalition now divides virtually evenly between the economically-focused managers and the culturally-conservative, viscerally anti-Washington populists. In 2008, according to an ABC news cumulative analysis of exit polls, the GOP primary electorate split almost exactly in half between voters with and without a four-year college degree; likewise just under half of Republican voters (44 percent) identified as evangelical Christians.
Bachmann is an ideal opponent for Romney because she electrifies the populist voters most resistant to him, but remains a hard sell for most managers. Perry is a vastly bigger threat to Romney because Texas' strong job-creation numbers gives him a much better chance than Bachmann of bridging the party's two camps by attracting managerial Republicans. Yet Perry's hard-right rhetoric and record (especially on social issues) makes it likely that he will still draw most of his support from the populist wing.
That dynamic creates the possibility that the populist voters most resistant to Romney will divide between Perry and Bachmann rather than uniting behind either. In theory, Romney could face a similar splintering of the managerial class if moderate former Utah Gov. Jon Huntsman develops into a serious competitor. But Huntsman fizzled at the Iowa debate and hasn't yet proven he will be a major factor.
If the current dynamics hold, the number of populist votes Perry loses to Bachmann will vastly exceed the number of managerial votes Romney loses to Huntsman. That could allow Romney to squeeze past his rivals with plurality victories not only in states like Florida and Georgia closely divided between the two camps, but even in contests such as South Carolina or Iowa that tilt toward the party's populist side.
That threat creates two instant imperatives for Perry. One is to maximize his reach into the managerial class. The other is to minimize Bachmann's populist support. The two goals are somewhat inimical. The former requires Perry to reassure; the latter to rage. Of the two, probably the higher priority for Perry is preempting Bachmann. If she solidifies her credibility by winning Iowa, she will likely siphon away a substantial number of populist votes from Perry almost everywhere else. That could derail the Texas governor, which means he has more at stake in beating Bachmann in Iowa than conventional wisdom now assumes.