Sen. Joe Lieberman, running as an independent after losing the Democratic primary, said Tuesday he hoped Democrats seize control of Congress — with one caveat: a Democratic-led Congress, he said, must change its ways.

"It won't represent progress that's real," Lieberman told reporters while stopping at a transportation forum in New Haven. "It's not going to be much of a step forward if there's a new Democratic leadership that doesn't change the tone in Washington."

As recently as Friday, Lieberman, a lifelong Democrat who was his party's nominee for vice president in 2000, would not say whether he thinks the nation would be better off with the Democrats in control of Congress.

Democrats must gain 15 House seats and six Senate seats to win control of Congress. Lieberman has said he would remain a member of the Democratic caucus if he wins on Nov. 7.

Lieberman has said he will not endorse Democratic candidates because he understands that his candidacy has put Democratic candidates in an awkward position, and has said he would stay out of their races.

Most leading state and national Democrats have endorsed Ned Lamont, a wealthy cable television company executive who has put some $10 million of his own money into the race, including $2 million this week. Republican Alan Schlesinger is also in the race, but trails in the polls.

Liz Dupont-Diehl, a spokeswoman for Lamont, said the three-term senator isn't taking responsibility for helping set the tone in Washington. Lieberman has called for an end to partisan politics, but Lamont has criticized him for siding too often with Republicans and President Bush.

"It's certainly hard to tell from Sen. Lieberman's comments that he's the incumbent," she said. "It seems that he's trying hard not to own up to the fact that he's been there for 18 years."

On Tuesday, Lamont faulted Lieberman for backing a 2005 energy bill that the Democratic candidate argues was a giveaway to big oil companies that sent gas prices soaring.

"That's the Washington of George Bush and Joe Lieberman," Lamont said in a speech at Eastern Connecticut State University. "That's the Washington they have defended together."

Lamont offered a plan to promote energy efficiency, alternative fuels and other renewable sources. He called for tax credits to help companies buy new fuel-efficent equipment and set a goal for the United States to use one quarter of its energy from renewable sources by 2025.

Lamont, the anti-war challenger, framed energy independence as a national security issue, "so we don't have to fight and lose loved ones in a desert in Iraq thousands of miles away."