If the Dim appeal has been and will be, "Raise taxpayers' taxes so we can give you tax eaters more Free Stuff", then all you can do is fight the bribe the best you can and GOTV among your own.
But that's not an argument for caving as the forehand option. Give up the principle, and you might as well go home; you're not doing anything, and everybody knows it.
The only problem is that is that is exactly what Obama did in late 2010 by accepting and signing extending all the tax cuts temporarily.
So that way not only couldn't the R nominee accuse O of raising those upper income taxes the cause of the economy problems, but Obama used that as an issue to beat Romney over the head endlessly with EVERY DAY. “That out-of -touch rich guy Romney is just protecting his rich buddies. We tried that and its not working. Why should you sacrifice when he is giving them even more and they are doing so good now?” was the O line.
So Dems didn't refuse the come out and vote because Obama gave in on those tax cuts at a strategically right time ( esp since they were temporary) , they rallied behind him when he made it an issue in the 2012 campaign against Romney.
If those taxes went up passed by the 2009 to 2010 Dem congress then Republicans would have had a real issue in 2012. I agree that Republicans couldn't come out looking like they were for raising taxes as that would defeat the whole idea, and they would have to be much smarter than they are to make this work.
So if they give in on taxes now after setting O up for re-election they will really look like complete fools. They lost everything. If they beat Obama+Dems back again now then not so bad.