People can appeal to swing voters regardless of where they are from. This isn't like NY where everyone outside of NYC hates NYC and erroneously thinks they are funding the city when it's actually the other way around. Portland is just Portland.

It's also not like ideological extremes are inherently disqualifying in Maine, as we can see by LePage being elected. Certainly we'd have better odds if we had a bog-standard democrat, and even better than that with a moderate one, but that doesn't mean the candidate has to come from outside Portland.

And there's also value in keeping your base on board. I think regional factors will largely be a wash in this type of state.