The Obama campaign is running the show so far in the campaign. Since Romney locked up the nomination, he has gone out of his way to say he supports lower student loan rates the same week Obama was scheduled to take up the issue. Now the issue of the past couple days has been the Obama campaign's attack on Romney's previous statements on whether he would send troops to another country to capture/kill bin Laden. While Romney did, as always, leave himself wiggle room in his original statements, having the topic in the discussion can only help Obama.
In August 2007, then-Sen. Obama stated he would be willing to send troops into Pakistan if he had actionable intelligence that bin Laden was there. Romney responded with a statement that our troops "shouldn't be sent all over the world" and "We want, as a civilized world, to participate
with other nations in this civilized effort to help those nations reject
the extreme with them". In other words, I want to make Pakistan get bin Laden, if that's where he is. A few days later at a debate he said he agreed that we would have the right to take bin Laden out of Pakistan but didn't agree that Obama should have made it explicit.
So if you really dive into it, Romney never said he wouldn't send troops to Pakistan to get bin Laden, but he's kinda wishy-washy about what he does say.
By comparison, Obama's argument is (paraphrasing) "I said I'd get him, and I got him." So it's a nice argument to be having.