I have never accepted the straw-man version of public-choice – a version in which that perspective on politics denies the role of ideas and ideology in shaping public policy. (George Stigler  is the most celebrated ambassador for that version of public-choice.)
Yet to deny that the typical politician will readily chuck away his or her principles for votes is naive. The latest piece of evidence on this front is Al Gore’s admission that he pandered, against his ‘principles,’ to voters in Iowa . (HT Manny Klausner) Here’s the key ‘graf, in which Gore explains why he voted for ethanol subsidies despite believing that they are poor public policy:
One of the reasons I made that mistake is that I paid particular attention to the farmers in my home state of Tennessee, and I had a certain fondness for the farmers in the state of Iowa because I was about to run for president.
Note that Mr. Gore refers to his knowingly selling his principles for votes as a “mistake.” Unless he means that his effort didn’t pay off with the top job in the White House, his soul-selling was no “mistake”; he knew exactly what he was doing and why he was doing it. His soul-selling was an instance, pure and simply, of the hypocrisy and lying that is the stuff of too many political campaigns.