Lamont, who defeated Lieberman in last week's Democratic primary, was trailing the 18-year incumbent in a new Quinnipiac University poll released Thursday.
The poll showed Lieberman, who is running as an independent, leading Lamont 53 percent to 41 percent among likely voters in a three-way race in November. Republican Alan Schlesinger gets 4 percent.
Lamont, who was joined Thursday on the campaign trail by former North Carolina Sen. John Edwards, said he thought the poll was "pretty good." He said the first poll taken during the primary race showed him 50 percentage points behind Lieberman, yet he still closed the gap to win that election.
"I've been focusing on the Democratic primary," he said. "But I think we've got a message that's going to do pretty well with moderates, independents and Republicans."
Though Lamont has gained ground, the poll found only 23 percent of registered voters have a favorable opinion of him. Twenty-eight percent have an unfavorable opinion and 25 percent are mixed.
Meanwhile, 43 percent view U.S., now running as an independent, favorably. Twenty-eight percent view Lieberman unfavorably, and 25 percent have mixed opinions.
"Lamont needs to be concerned because he has actually negative favorability right now statewide," said Quinnipiac Poll Director Douglas Schwartz. "He's popular among Democrats, but he's not doing well among Republicans and independents."
The poll found Lieberman leads Lamont among registered voters as well. Lieberman would garner 49 percent compared with Lamont's 38 percent, with Schlesinger getting 4 percent.
That's an improvement for Lamont, who trailed Lieberman 51 to 27 percent in a three-way race in a July 20 Quinnipiac poll. That survey of registered voters showed Schlesinger with 9 percent.
Meanwhile, the National Republican Senatorial Committee said Thursday that it does not intend to help Schlesinger financially.
"It's not a competitive situation at this point. We'll use our resources elsewhere," said Brian Nick, a committee spokesman, although he also added that the committee has "no intention of helping Lieberman."
Schlesinger said the poll's timing does not reflect his true level of support.
"This was taken immediately after the Democratic primary, and therefore there was a tidal wave of publicity for Lamont and Lieberman," Schlesinger said Thursday. "When people get to see me in debate and see the message I have for moderate and conservative voters, these numbers will change dramatically."
Also Thursday, Nancy DiNardo, chairwoman of the Connecticut Democratic Party, called on Lieberman to drop his independent bid. She added that Lieberman "respectfully declined" her request.
"It is my strong belief that Senator Lieberman should abide by the wishes of state party members and by the democratic process," DiNardo said in a statement.
Schwartz said the new poll contains more good news for Lieberman than Lamont.
Lamont "did make some progress. He did gain on Lieberman, but I think the more important news is that Lieberman still has a double-digit lead," said Schwartz, adding that Lamont had just come off a month of good news coverage and a stunningin which he won 52 percent of the vote to Lieberman's 48 percent.
"There is still time for Lamont to make this up," Schwartz said. "Lamont has to figure out a way to peel some of those soft supporters away from Lieberman."
Lieberman, a nationally known centrist who has been criticized by many Democrats for supporting the war in Iraq and a perceived closeness to President Bush, lost the primary by 10,000 votes. Political pundits say the primary was evidence of voters' frustration with the war and predict it could have national political ramifications.
Top state and national Democrats, including Sens. John Kerry, Ted Kennedy, Chris Dodd, Hillary Clinton and Frank Lautenberg, abandoned Lieberman after the primary and are endorsing Lamont.
Former North Carolina Sen. John Edwards, the 2004 candidate for vice president, campaigned Thursday with Lamont at a rally in New Haven with about 300 supporters. He later attended a fundraiser for Lamont's campaign. Edwards, who called Lamont after his primary victory, said his campaign is offering a change in politics that voters want.
Edwards also added his voice to those calling on Lieberman to drop out, despite the poll results suggesting the incumbent could run a strong race as an independent.
"I don't think it has anything to do with the polls," Edwards said. "This is about democracy. He's a Democrat, he ran in the Democratic primary, and he didn't win. Democrats chose Ned Lamont as their candidate, he should be the candidate."
The new poll showed that while 31 percent of registered voters are upset with Lieberman over his support of the war in Iraq and believe he should not be re-elected, only 7 percent of Republicans and 21 percent of independents hold that same view.
And despite the ill will that many Democrats have toward Lieberman, the former vice presidential candidate remains well regarded in some ways by the majority of Connecticut voters. Seventy-six percent of registered voters said Lieberman has strong leadership qualities, 74 percent said he's trustworthy and honest and 63 percent said he cares about the needs and problems they face.
Forty percent said Lamont has strong leadership qualities, 39 percent said he's honest and trustworthy and 41 percent said he cares about the problems they face.
Asked whether Lamont has the right kind of experience to be a U.S. senator, 33 percent said yes while 47 percent said no. Twenty-one percent didn't know. That's an improvement for the businessman since the July 20 poll, when only 24 percent said he had the right kind of experience.
"That's got to be a concern to Lamont," Schwartz said. "They value Joe Lieberman's leadership abilities and they question whether Lamont has the right kind of experience to be senator."
Some political observers believe that Lamont, to draw more moderate voters, should broaden his message beyond the anti-war campaign that has endeared him to liberal Democrats. Lamont has said that he feels confident about his ability to connect with voters on several issues, not just the war.
"I'm not going to change my issues at all. I'm going to keep talking the same way I have," he said Thursday. "I'm running against a career politician. I'm a guy who started up a business from scratch. I haven't been on the public payroll, I've met a payroll. I think I'm going to down and represent real change as an outsider in Washington, D.C."
Lamont, a multimillionaire, started a successful cable company, Lamont Digital Systems, with a bank loan in 1984. The firm has wired college campuses across the country.
His only political experience was on the local level, when he served two years as a Greenwich selectman from 1987-89. He also spent six years on the town's Board of Estimate and Taxation from 1989-95.
Lieberman's advantage comes from broad support among unaffiliated and Republican voters.
Thursday's poll showed Lieberman with 75 percent of the Republican vote, compared with 13 percent for Lamont and 10 percent for Schlesinger. Among unaffiliated voters, Lieberman garners 58 percent, compared with 36 percent for Lamont and 3 percent for Schlesinger. Among Democrats, Lamont leads Lieberman with 63 percent. Lieberman gets 35 percent of Democratic voters.
"It's good to be ahead in the polls again," said Lieberman, who was at a printing plant in Norwich Thursday morning touting his efforts to reduce electric rates. "I understand that early polling does not win campaigns. I consider myself to be behind in this race."
When pollsters asked whether Lieberman should drop out of the race because he lost the Democratic primary, 58 percent of all those surveyed said no, but among Democrats, 56 percent said he should.
The telephone poll was conducted between Aug. 10-14. Quinnipiac surveyed 1,319 registered voters and the poll has a sampling error margin of plus or minus 2.5 percentage points. Among the 1,083 likely voters, the margin of error is plus or minus 3 percentage points.