"George Bush's favorite Democrat," they call him. "Republican Lite," they sneer. But liberals are no longer just venting on Internet blogs and talk radio programs about their centrist nemesis: Senator Joseph I. Lieberman of Connecticut.Now, from across the nation, a determined alliance of antiwar activists is working overtime online and on doorsteps to defeat Mr. Lieberman, whose political moderation helped him earn the Democratic nomination for vice president six years ago. Their goal is not only to punish Mr. Lieberman for staunchly supporting the war in Iraq but also to protest what the activists consider the Democratic Party's willingness to accommodate President Bush.
Without a national race to focus on, thousands of activists from other states — encouraged by a host of liberal bloggers — have contributed money and volunteered to help the campaign of Ned Lamont, a cable television executive with little political experience who is trying to unseat Mr. Lieberman in the state's Democratic primary in August.
Although Mr. Lamont's challenge appears to be a long shot, it is roiling some quarters of the Democratic Party, just as the party is trying to regain control of Congress this year. Many Democrats assert that the vigorous challenge to Mr. Lieberman is overshadowing the governor's race and taking money and attention away from three closely contested House races in Connecticut that many strategists consider crucial to the Democrats' majority hopes. "It's absolute Democratic cannibalism," said John F. Droney, a former Democratic state chairman in Connecticut.