How Easy Will It Be for Ashton Carter to Work with Barack Obama?

I have written before that I am glad that Ashton Carter has been nominated to be secretary of defense. I am still glad. I think that he can be very good at his soon-to-be new job. But like Jennifer Rubin, I wonder whether the Obama administration will let Carter be good at his job. Carter has repeatedly said during his confirmation hearings that he will not shy away from giving the president his best advice, and it is entirely possible that Carter will succeed in getting the president to follow that advice. But I do wish that some senator would ask Carter whether he will resign if there remain the policy gulfs between him and the president that Rubin discussed. The answer might actually be somewhat revealing.