A spokesman said Lieberman needs just 7,500 signatures to qualify for the ballot as an independent. Lieberman lost the Democratic primary by a 52-48 percent margin to former cable TV entrepreneur Ned Lamont, who assailed Lieberman for supporting President Bush's Iraq war policy.
"The senator is focused on talking to the voters of Connecticut ... and he is confident they will give him another six years," the spokesman said. He acknowledged some of Lieberman's former primary supporters would no longer stay with him in the general election.
"The senator knows a lot of people are in a tough position and [he] is not going to hold it against them," the spokesman said. "It's politics. It's what happens."
Democrat Diane Farrell, who is challenging Rep. Christopher Shays, R-Conn., announced she is now backing Lamont. Farrell, who has campaigned vigorously against Shays and his support for the war, had endorsed Lieberman in the primary.
"I believe it is important to support the election process of our democracy, and I will support Ned Lamont as the Democratic candidate," she said.
Eli Pariser, the executive director of MoveOn.org Political Action, called Lieberman's defeat a rejection of the Iraq war and "a revolt by voters who are tired of politicians who are defending the status quo."
Pariser called on Senate Democratic leaders to insist that Lieberman not run as an independent. "Make sure Joe Lieberman does the right thing and the honorable thing," he said. "They need to actively intervene, take Sen. Lieberman aside, thank him for his service and ask him to step aside."
Pariser said his group would make phone calls in Connecticut urging voters to ask Lieberman not to run.