HARTFORD, Conn. (AP) – Down but not out, Sen. Joe Lieberman filed to run for re-election in November as an independent, saying Wednesday it would be “irresponsible and inconsistent with my principles if I were to just walk off the field.”

But top Democratic leaders threw their support to the anti-war challenger who defeated him on for the nomination, Ned Lamont.

In a statement issued in Washington, two top Senate Democrats said they “fully support” Lamont.

“The perception was that (Lieberman) was too close to George Bush and this was, in many respects, a referendum on the president more than anything else,” said Sens. Harry Reid of Nevada and Chuck Schumer of New York, the party’s leader and the head of its campaign committee.

Similarly, Lieberman’s fellow Connecticut senator, Chris Dodd, who had been campaigning for Lieberman, said he regretted his close friend’s decision and would now campaign for Lamont.

The final returns from Tuesday’s primary showed Lamont defeating Lieberman 52 percent to 48 percent.

Early Wednesday, the Lieberman campaign delivered two boxes of petitions to the secretary of state’s office, and aides said they contained more than enough signatures to qualify the three-term senator for the November ballot.

The move would set up a three-way race this fall among Lamont, Lieberman and Republican Alan Schlesinger, who has trailed far behind both Democrats in recent polls.

“I think it would be irresponsible and inconsistent with my principles if I were to just walk off the field,” Lieberman said in an interview with The Associated Press.

Lieberman said he not bothered by losing the support of his Democratic peers, noting he lost Tuesday’s primary even with their support.

“In the end the people make up their own minds and this is going to be a people’s campaign,” Lieberman said.

Lieberman said Wednesday that he fired his campaign manager and spokesman, and asked for the resignations of his campaign staff.

“We did not answer, adequately answer, the distortions of my record on Iraq and my relationship with George Bush, that the Lamont campaign put out,” said Lieberman, who said he didn’t blame campaign workers.

Lieberman’s 10,000-vote loss Tuesday sent shock waves through the local and national Democratic party. It was Lieberman’s first loss in a Connecticut campaign since 1980, and he’s long been one of Connecticut’s most popular Democrats.

Lamont won by hammering away at Lieberman’s support for the Iraq war and accusing him of being too close to President Bush. His campaign was embraced by liberal bloggers, who saw the campaign as a chance to take down an incumbent and play a bigger role in the Democratic party.

A Quinnipiac University poll released in July showed that 51 percent of likely voters would support Lieberman in a three-way race. That’s compared with 27 percent for Lamont and 9 percent for Schlesinger, an attorney who was formerly a lawmaker and mayor.

Though having both Lieberman and Lamont on the ballot could split the Democratic vote, Schlesinger is not considered a major threat. His campaign stumbled in July after revelations that he used a fake name to gamble at a Connecticut casino and had been sued over gambling debts at two New Jersey casinos. Republican Gov. M Jodi Rell urged him to drop out of the Senate race, but Schlesinger called the gambling a “non-issue” and vowed to remain in the race.

While Democrats urged Lieberman to drop out Wednesday, Republicans called his defeat a “shame.”

“Joe Lieberman believed in a strong national defense, and for that, he was purged from his party. It is a sobering moment,” Republican Party chairman Ken Mehlman said.

Lieberman had already filed paperwork to create a new party called Connecticut for Lieberman.

Creating a new party allows him to secure a position higher on the ballot than he would have if he petitioned as an individual. He will be fifth on the ballot under the new party, rather than eighth or ninth.

All signatures on the petitions turned in Wednesday must be validated by the town clerks in the towns where they were submitted. Those that are not will go back to the town clerks, who will have two weeks to verify them.