I don’t think there are any conservative Democrats. I do think there are plenty of Democrats who are going to vote in our GOP convention, who are going to vote for Obama in the general anyway, and are looking to vote for Santorum because they realize that he can be endlessly distracted over absurd questions and statements throughout the campaign. In fact, it isn’t a “I think” situation, it’s actually what they tell us they are doing:
http://www.dailykos.com/story/2012/02/28/1069045/-I-Voted-For-Rick-Santorum-This-Morning
The one constant of Republican nominees in my lifetime is Moderates (Liberals) lose general elections, Conservatives win general elections. If Romney does become the nominee, that constant won't change.