As VOA National Correspondent Jim Malone reports, Democratic opposition to the Iraq war appears to have played a key role in Lieberman's defeat.

Lieberman was defeated by fellow Democrat and political novice Ned Lamont - a man most Connecticut voters had never heard of until just a few months ago.

But in conceding defeat to Lamont, Lieberman announced he would run as an independent candidate in the November election in a bid to win a fourth term in the Senate.

"If the people of Connecticut are good enough to send me back to Washington as an independent Democrat, I promise them I will keep fighting for the same progressive new ideas and for stronger national security," he said. "That is who I am."

Challenger Lamont capitalized on liberal Democratic anger over the Iraq war and made Senator Lieberman's support for the U.S. military effort the central issue in the primary contest.

Lamont spoke to jubilant supporters after Lieberman acknowledged defeat.

"We have 132,000 of our bravest troops stuck in the middle of a bloody civil war in Iraq and I say it is high time that we bring them home to the hero's welcome," he said.

Joseph Lieberman was first elected to the U.S. Senate in 1988 and has long been a leading moderate in the Democratic Party.

Lieberman was Al Gore's vice presidential running mate in the closely contested 2000 presidential election.

Early in the race, few experts gave Ned Lamont any chance of upsetting three-term incumbent Lieberman in the Democratic primary.

But over the past year, liberal Democrats in Connecticut and elsewhere around the country have grown increasingly angry about the Bush administration's handling of the Iraq conflict.

Lamont accused Lieberman of being a cheerleader for President Bush and appealed to Connecticut voters to send an anti-war message to the rest of the country.

Political analysts say the Lieberman defeat suggests the Iraq war will be a defining issue in this November's congressional midterm elections.

"And there is no question in the Democratic Party that the anger against President Bush and the anger about the war is really the dominant thing on their minds," said Lewis Wolfson, who is a political expert at the American University in Washington.

Democrats hope to win a majority in one or both houses of Congress in November for the first time since Republicans took over both the Senate and House of Representatives in 1994.