Extending "All" the tax cuts (politically speaking)

Not getting into the merits of of the extensions for the richest few (or even the rest of us), it seems to me that politically the Rethugs simply can't bend on this if they really believe that that it is good for the economy that all the cuts be extended. If they make "permanent" the cuts for say everybody making less than $1M, $500K, $250K, or whatever the compromise figure turns out to be and then just extend for a couple of years the cuts for the remainder, they'll lose the issue mightily at the end of the extension period.

Assuming they are right and that the economy needs these cuts, it seems that if the economy is turning around at the end of the extension period then they will not find very sympathetic voters at that time like they did this election cycle. If I were the Rethug king and had to compromise, I'd probably choose to make all the extensions "temporary."