Paul Krugman says all the reasonable Republicans have been excommunicated from the movement:
Reasonable Republicans?: Several commenters have asked that I provide examples of Republicans making reasonable economic arguments; some of them seem to be saying that I’m proving my bias if I don’t provide such examples.
But it doesn’t work that way: if all Republicans are saying unreasonable things, then it’s a distortion — indeed, a form of bias — to insist that there must be reasonable Republicans.
Now, what you can quite easily find are examples of people who used to be Republicans, or even still consider themselves Republicans, saying reasonable things — say, Bruce Bartlett or David Frum. But the very fact that they’re reasonable has led to their excommunication from the movement!
It’s kind of the “treason never prospers” argument (“for if it prospers, none dare call it treason”); if someone declares that tax cuts don’t pay for themselves, or that printing money when you’re in a liquidity trap isn’t deeply inflationary, or that fear of Obamacare isn’t holding the economy back, he ceases to be considered a member in good standing of the GOP. There are, therefore, no reasonable Republicans on these issues.