Obama ran on a platform of ending the Bush tax cuts for the wealthy—and won.
If we go over the "fiscal cliff" and all Bush tax cuts expire, they know that the president will propose extending tax cuts for income under $250,000—and they don't want to "find themselves in the position of defending tax cuts for the highest income brackets."
They are pushing tax reform in the hopes of avoiding that scenario, but failing that, York said it's "unclear" whether they can stay unified in opposition to extending just tax cuts below $250,000.
As far as tax reform goes, Republicans want something like what Mitt Romney proposed: a cap on deductions. (York didn't go into detail on whether Republicans would push for the other part of Romney's plan, which was to lower tax rates by 20 percent. Obviously, it was the rate cut that created the biggest problem with Romney's plan, not the cap on deductions. Obama has already proposed a similar, but more modest, cap and Democrats are interested in pursuing the idea now that Republicans are floating it.)