The switch by the union, the American Federation of State, County and Municipal Employees, is the biggest labor boost Mr. Lamont has received since winning the Democratic primary last month....

Both Mr. Lieberman and Mr. Lamont had lobbied the municipal union for its endorsement, speaking to the union delegates personally on Friday. News of the endorsement was reported Monday in The Hartford Courant.

Sal Luciano, the president of the state union, said that the members became skeptical of Mr. Lieberman after the primary when several prominent White House officials suggested that they supported his independent bid in the general election.

“When he was running in the Democratic primary, we felt he had a good labor record and we owed him our endorsement,” Mr. Luciano said Monday. “When Joe switched in the general election, we became increasingly concerned with him moving closer to Bush. We know Ned will stand up to the Bush agenda.”

Lamont, who defeated U.S. Sen. Joseph I. Lieberman in a Democratic primary that focused on the war in Iraq, is part of a wave of Democratic candidates who think health care is the next galvanizing issue....

On Monday, Lamont toured Optimus Health Care, a busy, federally subsidized clinic on East Main Street, where about one-third of the patients are uninsured. Federal funding has been cut 1 percent, while costs have risen 14 percent in recent years.

"We're seeing more and more uninsured than we ever have before," said Ludwig M. Spinelli, the chief executive officer of Optimus.

"My take is we have a health care system that is broken and getting worse," Lamont said.

"I think it's a natural issue for Ned Lamont," [Senate President Pro Tem Donald] Williams said. "He is an employer. He has made payrolls and understands the need to attract and keep good employees."

During the 2003 consideration of President Bush’s destructive Medicare Part D bill, Sen. Joe Lieberman issued 8 press releases claiming he was outraged about the legislation and promising to do whatever he could to stop it. Yet, when it came time to vote on the bill and on amendments to fix the bill, Lieberman was nowhere to be found. He attended just 4 out of the Senate’s 38 votes on the Medicare bill, opting instead to hold fundraisers in California for himself so that he could add to the more than $1.8 million in health industry campaign contributions he has raked in over the last 6 years. By contrast, Ned Lamont has refused corporate and union PAC contributions, and has said it’s time for a Senator from Connecticut who isn’t afraid to show up, cast votes, and fight for real health care reform.