Voting your conscience or your constituency?

There was a whole lot that was fascinating about the Senate's recent rejection of an amendment that would have required states to honor each others' concealed handgun laws. One of the interesting aspects was that Republicans were essentially voting against states' rights. But whatever. The thing that caught the attention of observers locally was the little Kabuki theater played by Colorado's Democratic senators, Mark Udall and Michael Bennet:

Only two Republicans went against the gun lobby, but that was enough to leave supporters just short of the 60 votes they needed. The slim margin was no accident: Other Democrats, such as Pennsylvania's Bob Casey and Colorado's Mark Udall and Michael Bennet, were said to have been willing to vote "no" if necessary. Twenty minutes after the voting began, Bennet and Udall left the cloakroom together and walked into the chamber. Bennet went to the well to consult with Schumer, who indicated that it was safe for Bennet -- a product of D.C.'s St. Albans School -- to vote with the NRA. Bennet looked to Udall, who gave an approving nod, and cast his "aye" vote.

Colorado Democrats are atwitter about the true preferences of Bennet and Udall... especially the former, who is up for (re)election next year. Does he really believe that Colorado gun owners should be held only to the minimal conceal-carry laws of places like Alabama?

Political scientists Tim Groseclose and Jeff Milyo helpfully remind us that we shouldn't try to divine politician's individual preferences from their votes. As they note, if there is a conflict between constituency and conscience, it nearly always makes sense to screw your conscience and vote your constituency. The reason is that almost no roll call votes are decided by just one legislator. That is, no given senator's vote is likely to be pivotal. So if you vote your conscience, you anger your constituency and get no real policy benefit out of it. If you vote your constituency, you make your voters happy (or at least avoid making some important and active ones angry) and the policy outcome is the same regardless.