(AP) Sen. Joe Lieberman, facing a challenge from within the Democratic Party for renomination, said Monday he has not ruled out seeking a fourth term as an independent.

"I have not foreclosed the option," Lieberman said at a news conference at the Connecticut state Capitol. "If I wanted to run as an independent, I would. I'm running as a Democrat. I've been a Democrat all my life."

Ned Lamont, a Democratic activist and anti-war candidate from Greenwich, is challenging Lieberman for the party's nomination this year. He has been garnering support from some Connecticut Democrats dissatisfied with Lieberman's support of the war in Iraq and his perceived closeness with President Bush's administration.

The party will endorse a candidate at a convention on May 20.

Lieberman said he is not upset with fellow Democrats for opposing the war in Iraq. He, too, has criticized certain operations of the war and the Bush administration's handling of postwar Iraq, he said.

"I feel very strongly the world is safer without Saddam Hussein in power. We have to complete the job in Iraq," Lieberman said.

He asked that Democrats not solely judge him on the war, but also his record on the environment, economic development and his support for civil rights and civil liberties, he said.

Republican Paul Streitz who is seeking his party's nomination to challenge for the Senate seat, said he would gain if Lieberman runs as an independent.

"A Republican would win, obviously," he said. "It would split the Democratic vote."

Lieberman was in Hartford Monday to speak at a conference on global warming, and his critics also were there.

Keith Crane, a member of the Branford Democratic Town Committee, stood outside the conference room, holding a sign that said, "Some of my best friends are neo-cons."

Crane, who said he backs Lamont, will be a delegate at the state Democratic convention.

"I worked my butt off to be a delegate and he says if he doesn't get the nomination, he'll be an independent," he said of Lieberman. "He's not here for the environment. He's here for the political environment."

Howard L. Reiter, chairman of the political science department at the University of Connecticut, said an incumbent senator running without a party is not unprecedented.

Sen. Thomas Dodd was censured by the U.S. Senate in 1967 for financial misconduct and was denied renomination by the Democratic Party, which backed Joseph Duffey. Dodd ran as an independent and lost the general election to Republican Lowell Weicker, who was defeated by Lieberman in 1988.

"That's the precedent, but you have to go back 36 years," Reiter said.

Lieberman, his party's vice presidential nominee in 2000, unsuccessfully sought the presidential nomination four years later.