Ralph Nader announced his latest run for the presidency, amid press hoopla. I doubt that he’ll have a decisive effect this time. The reason? Everybody knows, in retrospect, that Nader’s participation in 2000 killed Gore’s chances. Given the intensity of anti-Bush feeling among the Democratic Left, Democratic voters are unlikely to chance a repeat of the 2000 experience (just as many Republicans and independents who had voted for Perot in 1992 were unreceptive to conservative and libertarian third-party candidates in 2000).
Not everyone learns from his mistakes, but most people do if the consequences are important enough. There’s no reason to expect Democratic voters to ignore history and plunge off the same cliff twice.
UPDATE: Jim Miller makes a different and more sophisticated argument that reaches the same conclusion about Nader as I did. However, Miller goes further and argues that Nader may not even have been decisive in 2000.