rous as it sounds, the real action migrated to New York’s 23rd, a rural Congressional district abutting Canada. That this pastoral setting could become a G.O.P. killing field, attracting an all-star cast of combatants led by Sarah Palin, Glenn Beck, William Kristol and Newt Gingrich, is a premise out of a Depression-era screwball comedy. But such farces have become the norm for the conservative movement — whether the participants are dressing up in full “tea party” drag or not.

The battle for upstate New York confirms just how swiftly the right has devolved into a wacky, paranoid cult that is as eager to eat its own as it is to destroy Obama. The movement’s undisputed leaders, Palin and Beck, neither of whom have what Palin once called the “actual responsibilities” of public office, would gladly see the Republican Party die on the cross of right-wing ideological purity. Over the short term, at least, their wish could come true…

The more rightists who win G.O.P. primaries, the greater the Democrats’ prospects next year. But the electoral math is less interesting than the pathology of this movement. Its antecedent can be found in the early 1960s, when radical-right hysteria carried some of the same traits we’re seeing now: seething rage, fear of minorities, maniacal contempt for government, and a Freudian tendency to mimic the excesses of political foes. Writing in 1964 of that era’s equivalent to today’s tea party cells, the historian Richard Hofstadter observed that the John Birch Society’s “ruthless prosecution” of its own ideological war often mimicked the tactics of its Communist enemies.

The same could be said of Beck, Palin and their acolytes. Though they constantly liken the president to various totalitarian dictators, it is they who are re-enacting Stalinism in full purge mode.