Independent? Moderate?
Precocity is right though: and the reason everything is being forced into the either/or is primarily because of the media, who need the good/bad WWE narrative to peddle the conflict (which means ratings) and of course both them and the parties don't want any third option anywhere near the debates (hello, Ron Paul!) because the American people might start thinkin' there's alternatives.
And we don't want that!
My problem with ideologies is that they prescribe means without consideration as to whether they deliver the ends.