Facing a stronger-than-expected Democratic primary challenge and sagging poll numbers because of his support of the Iraq war, U.S. Sen. Joe Lieberman said Monday he'll collect signatures for an independent campaign if he loses next month's primary.

"While I believe that I will win the Aug. 8 primary, I know there are no guarantees in elections," Lieberman told reporters on the steps of Connecticut's statehouse Monday. "No one really knows how many Democrats will come out to vote on what may be a hot day in August."

Lieberman said he will remain a Democrat even if loses his party's primary. He said he plans to remain a part of the Senate's Democratic caucus if re-elected.

"I will stay a Democrat, whether I am the Democratic Party's nominee or a petitioning Democratic candidate on the November ballot," he said.

Once a Democratic stalwart and the party's 2000 vice presidential nominee, Lieberman has fallen into disfavor from some Connecticut Democrats for his support of the Iraq war and his perceived closeness to President Bush.

Opponent Ned Lamont, a multimillionaire owner of a cable television company with little political experience, is capitalizing on the anti-war backlash and is accusing Lieberman of being a Republican lapdog who has strayed from his Democratic roots.

Quinnipiac University polls show Lamont's support among registered Democrats increasing from 19 percent in May to 32 percent in June. Lieberman's support in the same period fell from 65 percent to 57 percent.

Lieberman maintains high ratings among Republicans and unaffiliated voters. Unaffiliated voters are the state's largest voting bloc, followed by Democrats and Republicans.

The poll also found that if Lieberman runs an unaffiliated campaign, he would win with 56 percent of the vote, compared with 18 percent for Lamont and 8 percent for Republican Alan Schlesinger.

Lieberman said his decision was influenced by Lamont's wealth and concerns of a low primary turnout. Lamont has so far spent $1.5 million of his own money on the campaign.

"What if my opponent, who says he is worth somewhere between $90 million and $300 million, decides to write bigger and bigger checks in the last weeks of the campaign?" he asked.

Lieberman said he wants to take his case to the entire state should he lose the primary.

"My opponent in the Democratic primary is asking Democrats to vote against me because of position on one issue, Iraq," Lieberman said. "I'm asking Democrats in the primary in August and the general election in November to consider my total record."

Lieberman has until Aug. 9 — the day after the Democratic primary — to collect 7,500 signatures from registered voters to land on the November ballot as an unaffiliated candidate. Experts have said his petition drive during the primary could further annoy Democrats who already question his party loyalty.

As of Monday morning, Lieberman's office had not sought petitions to circulate for an unaffiliated campaign, said Dan Tapper, spokesman for Secretary of the State Susan Bysiewicz.

Lieberman's campaign said no date has been set for the signature collections.