I wonder what he'd do if the GOP won 50 seats and control of the senate came down to him
I tend to think he would only flip if the GOP did well enough to be favored to hold on in 2016. That would probably take at least 53 seats. However, he could semi-legitimately claim that it is always "in the best interests of Maine" for him to caucus with the majority party. So I could actually see him switch in 2015 and then back in 2017 on that rationale. If he is the deciding vote, I expect him to push for coalition control, probably with help from Collins and Manchin.
