It's a great point, and one the Republicans should be scared to death of, but the truth of the matter is: there is no way any Republican up for election in 2010 can support a public option opt-out and then not worry about what might happen in their primary or their political future in the Republican party. 

Look at how Charlie Crist has been demonized for supporting the stimulus … that's small potatoes compared to the backlash that would come from supporting the public option.  But then what happens if they oppose, win the primary, and have to face the rest of the public option friendly electorate? NY's 23rd anyone?