All the things that allow Romney to win the primary are unavailable to him to win the general and that’s why you see these Etch A Sketch comments because he knows he can’t win.
The reason Republican voters should be alarmed by the “Etch-a-Sketch” remark is the same reason they should have always been wary of Romney: he is thoroughly untrustworthy, he will say just about anything in order to win support, and there is every reason to assume that he will abandon current positions for new ones if he thinks it gives him an advantage. The “Etch-a-Sketch” remark suggests that Romney and his campaign believe that they can win if they are willing to be as shameless in their pandering during the general election as they were during the nominating contest. If Santorum’s slogan at this point is “we want a choice, not an echo,” Romney’s must be “I will echo whatever the electorate wants.”
This has nothing to do with Romney’s inability to outspend Obama during the general election. Romney and his campaign are putting their hope in the candidate’s exceptional lack of any consistent principles. It goes without saying that Santorum would have even fewer resources in the general election than Romney. What Santorum can’t admit is that his “different vision” isn’t all that different from Romney’s right now. It just so happens that Romney’s vision next year could be significantly different from Romney’s vision today.
Santorum’s argument is that a party secures electoral victory by “giving people a choice.” That can be true, but it is hardly guaranteed. People had clear choices in 1964, 1972 and 1984, and this worked to the advantage of the incumbent. When it works, it can lead to a major victory, as it did in 1980, but more often it results in defeat. Santorum is telling his supporters that voters reward sharp contrasts between candidates with victory for the challenger, which is another way of saying that they can have it all and don’t have to make any trade-offs.