WASHINGTON — Senate Democrats voted overwhelmingly yesterday to let independent Sen. Joseph I. Lieberman remain in their caucus, despite ill will over his campaigning for the Republican presidential nominee, Sen. John McCain of Arizona.

The former Democrat from Connecticut was pushed off the Environment and Public Works Committee, losing a subcommittee chairmanship on that panel, and he was admonished for his aggressive role in the election campaign.

But in what Lieberman and some Democratic colleagues portrayed as a gesture of partisan peacemaking partly inspired by President-elect Barack Obama, he was allowed to retain a major plum, his chairmanship of the Homeland Security Committee. That was a face-saving move that kept him in the majority caucus, which will hold at least 57 of the Senate’s 100 seats next year.

“This is the beginning of a new chapter,” Lieberman told reporters after the Democratic caucus for the 111th Congress voted 42 to 13 to welcome him back into the fold. He called the action “a resolution of reconciliation and not retribution.”

“Joe Lieberman is a Democrat. He’s part of this caucus,” Senate Majority Leader Harry Reid of Nevada told reporters after the party’s closed-doors session.

“I would defy anyone to be more angry than I was” about Lieberman’s role in the campaign. Besides endorsing McCain, a longtime friend and an ally on Iraq and other national security matters, Lieberman addressed the Republican National Convention on McCain’s behalf last summer and criticized Obama. Late in the campaign, he also made favorable statements about Sen. Susan Collins of Maine and another GOP senator seeking reelection.

But Reid suggested that it would have been the wrong course for Democrats to have purged Lieberman and then declared, “Boy, did we get even.”

Reid noted Lieberman’s work as a young man in the civil-rights struggles in the South, his decades of public service and his “progressive” record in the Senate.

Lieberman was Democratic presidential nominee Al Gore’s running mate in 2000 and four years later made an unsuccessful run for president himself. Lieberman lost the Democratic Senate primary over the war issue in 2006 but went on to win reelection as an independent. He was essential to the Democratic takeover of the Senate, caucusing with the party and adding his vote to make a thin majority of 51 to 49.

Lieberman declined in his remarks to reporters to talk about specific episodes or statements during his campaigning for McCain. But he said there are some “statements that I made that I wish I had made more clearly. And there are some that I made that I wish I had not made at all.

“And, obviously, in the heat of campaigns, that happens to all of us, but I regret that. And now it’s time to move on.”

Lieberman made a point of thanking Reid and several other colleagues — including fellow Connecticut Sen. Christopher J. Dodd — for working to keep him in the caucus.

Rhode Island Senators Jack Reed and Sheldon Whitehouse both supported the leadership resolution that kept Lieberman in the caucus as Homeland Security chairman and as a member of the Armed Services Committee.

Whitehouse said Lieberman has supported Democratic leadership policy “frankly, on every issue” — with the major exception of his backing of President Bush on the war in Iraq.

Reed said Lieberman helped his cause by declaring his support for the new administration and for Democratic leadership.

Reed said one of the most important factors in yesterday’s action was Obama’s suggestion that Democrats “begin this new Congress in a spirit of cooperation, not confrontation.”

jmulligan@belo-dc.com