Isn't his senate seat up in the same year? If so, he has more decisions to make.
It is.
If so, he has more decisions to make.
What decisions? He'll obviously run for re-election for the Senate, since there's no guarantee that he'd win the general, hell, he'll have a tough enough time winning the primaries. He's not going to risk falling into complete obscurity when he can have a high-profile, fallback job to go back to. And he won't have any problems running for both at the same time--even if he doesn't spend one second campaigning there, MA will re-elected him to the Senate. And if there is a law that a person cannot run for two federal offices at the same time, the dems in the state legislature will change the law, yet again, to favor their boy--just like they did over who would get to appoint Kerry's replacement had he won.