…should there be a two-way race for the Senate seat (and that's by no means a sure thing), Republicans will need a candidate who can run as a Snowe Republican. The currents of 2010 affect their ability to field such a candidate.
That's U. of Maine political scientist Amy Fried in this post. See also her earlier piece with Douglas Harris, “Maine’s Political Warriors: Senators Snowe and Collins, Congressional Moderates in a Partisan Era.” Here is their graph of the changing partisan composition of New England’s congressional representatives:
See also this post by Peter Ubertaccio. And this post by Keith Poole and this post by Simon Jackman, who writes:
Should the Democrats pick up the seat, we might expect a Senator racking up a voting history a la Levin (D-MI), Stabenow (D-MI) or Cantwell (D-WA) or Murray (D-WA), right in the middle of the Democratic pack.