A number of commentators seem shocked at how unreasonable Republicans are being. "Has the GOP gone insane?", they ask.
Why, yes, it has. It's the culmination of a decades-long process. The modern GOP does not accept the legitimacy of any Democratic President (see Clinton then, Obama now). As a result, they are automatically against anything a Democratic President wants, even if they've supported similar proposals in the past.
Voodoo economics has taken over the GOP. Supply-side voodoo -- which claims tax cuts pay for themselves and/or that any rise in taxes leads to economic collapse -- has been a powerful force in the GOP since Reagan.
The GOP has gone off the deep end. If you're surprised, that means you were part of the problem.