One person who came to mind when I was processing Charlie Crist's poll numbers the last couple days was Olympia Snowe.
Crist and Snowe are the only two politicians I can think of who we've polled in the last year and found to be more popular with voters in the other party than in their own.
Snowe's up in 2012, and in one respect I could see a similar plight for her to Crist. We found back in November that 59% of Republicans would prefer to nominate a more conservative challenger to her the next time around compared to only 32% who would pick Snowe. Those numbers are very similar to the 60/28 lead we found for Marco Rubio over Crist. Certainly Snowe has a couple years to make Maine Republicans happy with her again, but it could be a hard fight for renomination.
Snowe's prospects for getting reelected as an independent- or even as a Democrat- are a lot better than Crist's though.
For one thing Maine is open to electing independents- 2 of the last 5 Governors were. More importantly for Snowe in comparison to Crist is that while Republicans have soured on her a little bit she still has very good numbers with Democrats (60/29) and independents (51/33). Her popularity with those groups has kept her overall approval rating over 50%, a standing few Senators are reaching these days.
Maybe the far right will give Snowe a free pass on the assumption that she's as good as conservatives are going to get in a state like Maine. But her best path to reelection might come outside the Republican Party.