It was a lonely farewell for Joe Lieberman.

When the senior senator from Connecticut stood to give his parting address Wednesday afternoon [See Verbatim on facing page], onlyone colleague, Delaware Democrat Tom Carper, was with him on the Senate floor.

As Lieberman plodded through his speech, thanking everybody from his wife to the Capitol maintenance crews, a few longtime friends trickled in.

In came John Kerry of Massachusetts, who bested him in the 2004 Democratic presidential primaries and then, like many Senate Democrats, endorsed Ned Lamont, who tried to oust Lieberman from his Senate seat in 2006.

In came Susan Collins of Maine, Lieberman’s Republican counterpart on the Homeland Security Committee, whom Lieberman supported over a Democrat in her 2008 re-election.

In came GOP iconoclast John McCain of Arizona, who was close to naming Lieberman as his vice presidential running mate in 2008, which would have made Lieberman the first man on both a Democratic and a Republican national ticket.

A few more senators arrived during the 20-minute speech, but even by the end Lieberman was very much alone, which is how it has been for much of his 24-year tenure. He tried to push back against the mindless partisanship that developed in the chamber, and he paid dearly for it.

Lieberman was excommunicated by his party (he won as an independent in 2006 after losing the Democratic primary) and retired this year rather than face probable defeat. Yet he received little love from the Republicans, either, because despite his apostasies on key issues — the Iraq war, above all — he remained a fairly reliable vote for the Democrats.

The sparse attendance wasn’t unusual for a farewell speech, but it was a sad send-off for a man who was very close in 2000 to becoming a major figure in American political history as the first Jew on a major party’s national ticket. He was denied the vice presidency not by the voters but by the Supreme Court. As he joked in his farewell speech, he was “grateful to have received a half-million more votes than my opponent on the other side — but that’s a longer story.”

Six years later, he was drummed out of his party because of his willingness to embrace Republicans (he received a kiss from George W. Bush after a State of the Union address).

And so it was a man with few political allies who bid the chamber farewell. “I regret to say as I leave the Senate that the greatest obstacle that I see standing between us and the brighter American future we all want is right here in Washington,” he said. “It’s the partisan polarization of our politics which prevents us from making the principled compromises on which progress in a democracy depends.”

Lieberman’s career shows the perils of resisting the polarity. I’ve followed Lieberman since his first Senate run in 1988, when I was in college in Connecticut with his son, Matt. I was on the campaign trail with Al Gore in September 1998 when Lieberman gave his famous speech on the Senate floor opposing Bill Clinton’s impeachment; the Gore staffers exulted, believing Lieberman had just saved Clinton’s presidency and Gore’s prospects. I was also in St. Paul, Minn., in 2008, when Lieberman, in one of his less-proud moments, sealed his estrangement from the Democratic Party by addressing the Republican convention.

Lieberman did not attempt to settle old scores Wednesday, and he avoided his trademark sanctimony. He made one last appeal to his colleagues to “support, when necessary, the use of America’s military power” and “have the patience and determination when the public grows weary to see our battles through until they are won.”

Mostly, he offered fond reminiscences of a quarter-century. “When I started here in the Senate, a blackberry was a fruit and tweeting was something only birds did,” he said, then recalled some of the legislation he brokered: the 9/11 Commission, the Department of Homeland Security and repealing the ban on gays serving openly in the military.

“There is no magic or mystery” to how such things were done, he said. “It means ultimately putting the interests of country and constituents ahead of the dictates of party.”

Lieberman did that, and it ultimately ended his career.

He finished his speech and accepted hugs and handshakes from staff members and the few senators on the floor. Then he slipped out one of the chamber’s south doors and into the Democratic cloakroom — a place that had never really been his home.