I think Josh Marshall has it exactly right, Romney Telegraphing Loss:

As noted this morning, Wednesday April 11th is day one of the general election.  But there are things I’m seeing that tell me that Mitt Romney is kicking off the campaign in a telling defensive posture.  What I mean is that on various fronts, Romney is kicking off within Obama’s campaign narrative.  He’s living in Obama’s world, playing on his turf.

Example one is the Romney campaign’s push that it’s Obama’s economic policies that are the real “war on women.”

The effort to point to an “Obama Rule” over and against the “Buffett Rule” looks the same to me.

This might be a good talking point at some level.  It gives the campaign an affirmative argument on a big issue, which is always at least a bit better than having nothing to say at all.  But fundamentally, this is Obama’s turf.  It’s me-too.  And you hope to keep up that way, not win.

The presumptive Republican nominee needs to create his own campaign themes, not just take slaps at Obama’s campaign themes.  What worked in the primaries will not work in the general election for a variety of reasons.