Has the First Pundit concluded that Mitt Romney has won the Republican nomination? That’s the implication of today’s shift in Obama campaign tactics, in which David Axelrod blasted Romney for flip-flopping, and in particular for opposing the extension of the president’s payroll tax cut. As David Nakamura reports, Axelrod’s main theme in his call to reporters today was flip-flopping and trust:

Across the political spectrum, people have the same question: If you are willing to change positions on fundamental issues of principle, how can we know what you will do as president? How can we trust who you are?

It’s a coordinated hit; Democratic National Committee Chair Debbie Wasserman-Schultz echoed Axelrod’s points today, and earlier in the week the DNC debuted a Web site devoted to hitting Romney for flip-flops.

The thing is that the flip-flop attack, and in particular attacking Romney on specific economic issues, is a general election strategy. That contrasts with the previous Obama plan of tweaking Romney by emphasizing how much the two had in common, particularly on health care. In fact, with new details reported just yesterday about the links between Romneycare and the Affordable Care Act, Axelrod and the Democrats certainly could have chosen to once again embrace the Massachusetts plan — thus keeping the connections in the news and creating trouble for Romney within the GOP nomination battle. But instead, the Obama campaign moved on to an issue that they presumably hope will resonate with swing voters next November.

If anything, Obama character attacks on Romney are apt to help him with partisan Republicans, who can be counted on to automatically reject anything the White House says (health-care attacks wouldn’t work because conservatives would believe Obama, but because they would encourage everyone to talk about the issue, which can only work against the Mittster).

So assuming that Obama would rather avoid facing Romney, the obvious question is: Does the Obama campaign think the GOP nomination battle is all over but the shouting? I agree with Seth Masket and Jonathan Chait that Rick Perry remains viable, but could it be that David Axelrod and David Plouffe disagree? It certainly would explain this week’s new theme rollout.