Beinart puts Romney's private equity background in perspective:
There’s a reason Newt Gingrich and Rick Santorum went after Bain: because Romney’s super-rich, out-of-touch image was hurting him among white, working-class voters. And as The New Republic’s Alex MacGillis has shown, Ted Kennedy’s campaign used Bain’s layoffs to devastating effect in his Senate victory over Romney in 1994. The Kennedy folks even flew workers laid off by companies Bain had invested in to Massachusetts to campaign. …
Obama can’t win reelection simply with the votes of young, single, and minority voters. He needs to hold down his losses among blue-collar whites, a group with which he has always struggled. Using Romney’s stewardship at Bain to drive a wedge between him and the culturally conservative working-class whites whose turnout he desperately needs made a lot of sense, especially if the Obama campaign had tied Romney’s record at Bain to his support for unpopular Republican budgetary proposals.
Along the same lines, Nate Cohn finds little evidence that Obama's Bain attacks have backfired.