[P]ayroll-tax cuts are the sort of tax break most likely to "get the economy moving again" during a recession. (Because they put money in the hands of people most likely to spend it and therefore boost other businesses. And on balance they lower the cost of adding new workers.) Income-tax breaks at the top end are least likely to create new demand or jobs. (Because they go to people who have a lower "marginal propensity to spend" and are more likely to park the money in the bank.)
Makes sense to me. I'd reckon that, if they made this a really big issue, Democrats, Liberals, and Progressives might start cracking the false narrative of Republican Tax Relief, kneecap support for the Bush Tax Cuts, gain some desperately needed political capital, and hammer the GOP on a fundamental economic vision for America. This situation, after all, proves beyond a shadow of a doubt that Barack Obama cut taxes so that working people and small businesses were the primary beneficiary. It also demonstrates that Republicans, who have literally picked "not raising taxes" as their hill to die on in the Debt Ceiling debates, are actually willing to raise taxes whenever it is politically convenient to do so.
And by "raise taxes," I'm using the GOP definition which includes: letting certain tax cuts expire, closing loopholes, ending subsidies, and the spectre of raising taxes at some future time.
So now that we've determined what kind of tax opponnents Republicans really are, all that's left is negotiating. Oh, and spreading the word to the American people before the GOP is able to work its way onto both sides of this issue as well.