The Republican Party's big squeeze
Over the last few years, Republicans have been retreating from policy ground they once held and salting the earth after them. This has coincided with, and perhaps even been driven by, the Democratic Party pushing into policy positions they once rejected as overly conservative. The result is that the range of policies you can hold and still be a Republican is much narrower than it was in, say, 2005. That's left a lot of once-Republican wonks without an obvious political home.