Loud, but not representative
This bears repeating. We've heard before that lawmakers tend to presume their own districts are much more conservative than they are, but it's the degree to which they're off that's
amazing, and important.
The typical conservative legislator overestimates his or her district’s conservatism by a whopping 20 percentage points. Indeed, he or she believes the district is even more conservative than the most right-leaning district in the entire country.
Liberals also think their constituents’ views are more conservative than they really are, but are typically only off by about five percentage points.
So when Republican lawmakers get to Washington, they are operating under the presumption that their districts are full of insane people who are more conservative than any of the sorry bastards in anyone else's district. And thus a hundred Ted Cruzes get their wings. (On the Democratic side, they are
still convinced their constituents are more conservative than they, which likely accounts for the depressing tendency of lawmakers to agree to conservative demands even when the actual polling of the district shows their voters don't want anything of the sort.)
Why does this happen? There's probably a few reasons, and they're probably testable. First, the far-right is unequivocally better at rallying their members to contact Congress and yell at them for not doing the most conservative possible thing. Our side has been trying to get better at that—hence the calls to sign petitions or call your congresscritters that popup on our site on a regular basis, as reminders that all of the grumbling in the world won't strengthen the congressional spine unless they hear it—but as anyone who has ever listened to CSPAN call-in segments can attest, conservatives are much louder than liberals and seem to have a lot more free time on their hands.
The second and probably equally significant reason is the steadfast conservatism of the pundit corps. The papers of record are filled with certified-important people demanding objectively far-right things, including in the unsigned op-eds of the papers of record themselves. For every "liberal" like Krugman there is a Krauthammer, a Kristol, a Brooks, and six others besides all demanding neoconservative interventionism, or conservative "austerity" focused almost entirely on the lower classes, or that we recognize that black Americans don't have it all that bad, they just lack character, and so on and so forth. This extends to the Sunday shows, and to cable news interviews; the same voices rotate in and out of the same chairs espousing the same positions, and that those positions are largely the voices of a wealthy, privileged and very-right-of-center American minority does not matter; it is declared to be what America thinks, even when the actual polls frequently show actual America doesn't think anything of the sort.
That's a thornier problem to deal with, because it's cooked into the current system. Our political class, our punditry class and our wider political media establishments operate by currying favor and fame within their own social sphere. That sphere does not include "constituents." At very best, it might include the thoughts of a cab driver here and there, but only when the important people find themselves needing to go somewhere and bereft of other story ideas at the exact same time.