Obama, in an interview with an ABC affiliate, hits Mitt Romney again over Bain:

Well, here’s what I know, we were just talking about responsibility and as president of the United States, it’s pretty clear to me that I’m responsible for folks who are working in the federal government and you know, Harry Truman said the buck stops with you.

Now, my understanding is that Mr. Romney attested to the SEC, multiple times, that he was the chairman, CEO and president of Bain Capital and I think most Americans figure if you are the chairman, CEO and president of a company that you are responsible for what that company does.

Ultimately Mr. Romney, I think, is going to have to answer those questions, because if he aspires to being president one of the things you learn is, you are ultimately responsible for the conduct of your operations, but again that’s probably a question that he’s going to have to answer and I think that’s a legitimate part of the campaign.

The Obama campaign is moving the argument away from the details over whether Romney was directly involved in the post-1999 controversial deals and onto the more general question of whether Romney is willing to take responsibility for the activities of a firm during the period in which he was listed as its CEO and chairman.

This comes as new evidence is emerging that Romney’s relationship with the firm after 1999 — when he said he left — may have been more complex. Dave Weigel notes, for instance, a 1999 Boston Herald article saying: “Romney said he will stay on as a part-timer with Bain, providing input on investment and key personnel decisions.” And Jed Lewison points to a press release distributed on Bain’s behalf that described his leave of absence from the firm as “part time.”

I don’t know how conclusive this new stuff is. But here’s the point: There are two separate questions here that don’t necessarily have the same answer. The first: Was Romney directly involved in the controversial post-1999 deals? We don’t have evidence he was. Based on what we know now it’s unfair to tag Romney personally as an offshorer. The second: Even if we accept Romney’s claim that he had no managerial involvement, should Romney still be held partly responsible for — and is it fair to associate him with — the activities of a firm at which he was listed as chairman and CEO?

The lack of evidence on the first question does not mean the answer to the second question is No. Brad De Long says the answer to the second question is settled — he’s partly responsible. That’s fine, but ultimately, the argument over that second question is a political argument, one that will be settled if the public renders a verdict on it. And this argument is a tough one for Romney to win; what’s more, it feeds into the larger case about Romney’s character the Obama campaign is trying to make. Which is why Obama is now directly trying to engage him on it.