A prominent US Democratic senator says he is planning to run as an independent candidate after losing a mid-term primary in Connecticut.
Senator Lieberman has represented Connecticut for 18 years
Joe Lieberman, who stood for vice-president in 2000, lost to anti-war newcomer Ned Lamont.
He spoke against "partisan bickering" and vowed to campaign for "a new politics of unity and purpose".
Mr Lieberman, a senator for 18 years, has been harshly criticised in his home state for his support for the Iraq war.
With most of the votes counted, results showed Mr Lamont to have won with 52% compared with Mr Lieberman's 48%.
To run as an independent candidate, Mr Lieberman must gather 7,500 signatures by the end of Wednesday.
"The old politics of partisanship won today - I cannot and will not let that result stand," he said.
Mr Lamont, founder of a cable television company and a political novice, capitalised on the war's unpopularity in Connecticut to leap over Mr Lieberman.
Winner Ned Lamont gained support from liberal Democrats
Mr Lieberman - who was Al Gore's running mate in 2000 and who sought his party's nomination for the 2004 presidential campaign - has been labelled by some Democrats as being too close to Republicans and President George W Bush.
But his defeat sends a message to politicians of all colours that Iraq is becoming a political liability - an impression backed up by a recent opinion poll, reports the BBC's Nick Miles in Washington.
The poll, conducted for the Washington Post and ABC Television, suggests only 53% of people are happy with their representatives in Congress - almost identical to the situation in 1994, the year Democrats lost control of both houses of congress.
1942: Born in Stamford, Connecticut
1970: Elected to Connecticut State Senate
1983: Elected as Connecticut attorney general
1989: Wins bid for US Senate
2000: First Jewish candidate for vice president
Unsuccessful bid for 2004 presidential nomination
Then, the economy was the deciding factor - but the poll suggests the issue today is the Iraq war, our correspondent says.
Many more Democrats than Republicans are unhappy about the war, suggesting that support for the war could prove particularly costly to some Democrat congressmen.
Primaries were also held in four other states.
Colorado, Missouri, Michigan and Georgia have also been voting to choose candidates who will contest this November's elections to Congress.
In Georgia, Representative Cynthia McKinney lost in her bid for Democratic nomination.
Attorney Hank Johnson beat her with 59% of the vote.
In Michigan, moderate Republican lawmaker Joe Schwarz was beaten by conservative Tim Walberg, a former state legislator.
In Missouri, the primaries for the Senate race were won by Republican Senator Jim Talent and Democratic state auditor Claire McCaskill.