Somebody wants to be President.
Right... because this will help him win over the primary voters.
It'll help ensure he gets reelected this November. If he doesn't do that he'll have as much chance of getting the nomination as an ex-Senator does. Granted, he looks like a sure thing for reelection now, but if he takes it for granite, he might not be. Ten months is a long time in politics.
Yes, and even if this is all calculated political theater (which I do't think it is), it never hurts to have a geographic base in the primaries. While they obviously don't vote R in the General, the NE states still have a lot of primary delegates.