Hartford, Conn. ? In a stark repudiation, Sen. Joseph Lieberman, D-Conn., narrowly lost the Democratic Senate primary here Tuesday night, falling to antiwar candidate Ned Lamont in a campaign that became a referendum on the incumbent’s support for the Iraq war.

Lieberman publicly conceded the primary shortly after a congratulatory call to Lamont. But he appeared almost exuberant in defeat, telling supporters at a hotel in Hartford that he planned to run as an independent in November and predicting that he would be returned to the Senate for a fourth term.

Lieberman, accused by many in his own party of being an accommodationist to President Bush, also made clear that he would try to make the general election a campaign about the tone and style of politics that he said has stalemated Washington and that he charged was at the heart of Lamont’s insurgency.

Businessman Ned Lamont celebrates his victory over incumbent Sen. Joe Lieberman in Tuesday's Democratic state primary at the Four Points Sheraton in Meriden, Conn.

“I am of course disappointed by the results but I am not discouraged,” Lieberman said. “I’m disappointed not just because I lost but because the old politics of partisan polarization won today. For the sake of our state, our country and my party I cannot and will not let that result stand.”

Lieberman faces potentially substantial hurdles in his independent candidacy, despite a poll taken early in the summer showing him winning a three-way race easily. He is likely to face a party united in opposition to his candidacy, at least on the basis of their public statements of support for Lamont. Lieberman hopes to attract moderate independents and many Republicans while holding on to at least part of his Democratic support.

Democratic Sen. Joe Lieberman had a positive attitude while leaving the polls Tuesday, but things took a different turn later when he lost in the Connecticut primary election.

Lamont, who was given little chance of winning when he launched his campaign in the spring, appeared moments later before a cheering, chanting crowd of supporters at a victory party in Meriden. “They call Connecticut the land of steady habits,” he said to supporters. “Tonight we voted for a big change.”

Saying the time has come to “fix George Bush’s failed foreign policy,” Lamont said he would push for a withdrawal of U.S. forces in Iraq. “I say it’s high time to bring them home to a hero’s welcome,” he said, as his supporters began to chant, “Bring them home, bring them home.”

In his victory speech, Lamont praised Lieberman for his service to the state but added, “I’m hoping that over the course of the next few days that we’ll come to the conclusion that the party’s going to stick together and we’ll go forward united.”