Alan Greenspan, the former chairman of the Federal Reserve, goes to a lot of parties. He and his wife, the TV journalist Andrea Mitchell, "sort of get invited everywhere," he says, sitting in front of the long bay window in his office on Connecticut Avenue in Washington, D.C. Lately, though, cocktails and dinners seem to have guest lists drawn almost exclusively from one political party or the other. "It used to be a ritualistic 50-50 at parties—the doyennes of culture and partying were very strict about bipartisanship," he adds. "That doesn't exist anymore."

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