Yes, but not many of them can without being seen as flip-flops. Santorum is trying and failing miserably.
For once I agree, they can try… but for most their readiness to be closely linked with the President while he was popular, makes it nearly impossible for them to distance themselves unless they have a record of being independently minded like McCain or Voinovich, and in reality very few have.
And its true that Santorum’s attempts to cast himself as “independently minded” have totally failed, simply because he has always been firmly weded to the GOP leadership and the Bush Administration.
If things continue as they are at the moment, there will be a traditional anti-majority party mood next fall, in contrast to the congressional races in 02 and 04 and that could be very bad news for the GOP, even when the seats being contested favour them over the Democrats.