Grover Norquist has a majority of the House of Representatives under his thumb. 219 representatives have signed his pledge (.pdf) to never raise taxes on anyone ever, and that's enough to keep a deal from happening. Of course, Norquist himself actually has no official power. He doesn't decide who is on the ballot. But, as demonstrated in the GOP primary defeats of relative moderates like Richard Lugar and Bob Bennett, any Republican who shows any hint of being insufficiently conservative is not long for this political world. A Republican who breaks a pledge to Norquist would certainly face a primary challenger supported by Norquist and Co., and that Republican would almost certainly lose.
Republican voters have shown no inclination to encourage compromise or moderation. It would take an act of political courage for a Republican to challenge his own constituency to change their stance. GOP voters have so routinely purged legislators capable of legislating that there is no one left foolish enough to fight the status quo.
So now we have a 219 representatives who would be committing career suicide if they led the nation away from the fiscal cliff. With a majority of the House sworn to never raise taxes, along with a president who's said he will veto a cliff-avoiding bill that doesn't raise taxes on the rich, I'm not optimistic that we can avoid a Washington-induced recession.