Connecticut Sen. Joseph Lieberman’s announcement that he will not seek re-election in 2012, when his fourth term expires, has unleashed critics and admirers alike. All seem anxious to weigh in on the legacy that the controversial Democrat-turned-independent will leave when he wraps up two dozen years in the Senate — and a lifetime of elective public service.

In an expansive interview Thursday with NPR, Lieberman, 68, expressed little regret for decisions he has made, including those that continue to infuriate many Democrats: from his staunch support of the Iraq war and opposition to a public health insurance option, to his support of 2008 Republican presidential candidate Sen. John McCain.

“I felt at the time that [McCain] was just plain the best prepared to be the president we needed at that time,” Lieberman said. “Enjoying the independence I had, as an independent, I did what I thought was best for the country at the time.”

Lieberman says the “most gratifying” political moment of his career was retaining his Senate seat in 2006 as an independent, after losing the Democratic primary to wealthy anti-war candidate Ned Lamont.

But Lieberman, who in 2000 became the first Jewish American named to a national party ticket when Democratic presidential nominee Al Gore chose him as his running mate, says he’ll never get over the Supreme Court’s Bush v. Gore decision, which made George W. Bush the winner of that disputed election.

“I’ve never really come to terms with the decision in Bush v. Gore,” he said. “I thought it was just a bad decision, a wrong decision from a legal point of view.”

He added: “I’ll forever be really angry about the Supreme Court decision and the way it ended.”

Lieberman, who has invariably proved as durable as his many critics, said he had a “good day-after feeling” about Wednesday’s announcement that he will not seek another term. And it was a day-after with no excuses, and fewer regrets.

As for his remaining time in office, Lieberman asserted that, despite the ill will that many liberals hold toward him, he will remain in the Democratic caucus — though he appeared to leave the door open a crack.

“There’s no reason I would change over the next two years,” he said, “that I can foresee.”

Highlights of the interview are excerpted below. You can read the entire transcript here.

Liz Halloran: You have been characterized as a moderate by some, as an opportunist by your critics. That being said, what are the prospects going forward for moderates in Congress?

Sen. Joe Lieberman: The question of the future for moderates has to be divided between their prospects in the United States Senate and their prospects in American politics. And here’s what I mean: Moderates play an increasingly important role in the United States Senate, because without moderates in both parties, you don’t have the bridge builders to bring the parties together to get anything done.

According to most measures, in the past few years you have voted with liberals 50 to 60 percent of the time, and conservatives 40 to 50 percent of the time — joining liberals on key votes including CAFE [fuel efficiency] standards, greenhouse gas caps, giving illegal aliens a path to citizenship, and prosecuting hate crimes. But you’re against withdrawing troops [from Iraq and Afghanistan] and establishing a public health insurance option. How would you characterize yourself at this moment? What are the chances you’ll caucus with the Republicans?

I’m in the Democratic caucus, though I am an independent. There’s no reason I would change over the next two years that I can foresee. Secondly, I characterize myself as independent-minded. Like most Americans, I don’t feel that I have to decide every issue based on a party-line orthodoxy. Seems to me most Americans look at every issue separately and decide what they think makes most sense. And yet somehow in politics, both parties expect elected officials to just toe the party line. And why should we?

How did you come to terms with the Supreme Court’s Bush v. Gore decision that cost you the vice presidency? I understand it was devastating, but was there something that led you to acceptance?

No. I will tell you that I’ve never really come to terms with the decision in Bush v. Gore. I thought it was just a bad decision, a wrong decision from a legal point of view.

Do you think about every day?

Life goes on. This happens to be the way I was raised — the way a lot of us were raised. Life is not about yesterday; it’s about today and tomorrow. Whenever I go back to it and think about 2000, I’m extremely grateful to Al Gore for the historic opportunity he gave me, and it was totally his decision. I’m proud of the campaign he and I ran. And I’ll forever be really angry about the Supreme Court decision and the way it ended. You know, you can’t live in the past. The day after Al and I conceded, I went right back to my Senate office in the morning and went back to work.

Do you have any regrets that you concurrently ran for the Senate in 2000?

Oh, God, no. I’m so grateful that I did, because I love service in the Senate and I didn’t want it to end if for some reason we didn’t win the national election.

You couldn’t get traction in the 2004 race for the Democratic presidential nomination, and in 2006, you suffered a bitter defeat when Connecticut Democrats in a primary rejected you for a well-financed anti-war candidate. You went on to win in the general election, obviously, as an independent. How much did that repudiation by your party figure into your endorsement of Republican Sen. John McCain in the 2008 presidential race?

It did not figure into my endorsement of Sen. McCain as an act of revenge. Let me be very clear about this. Losing the primary in 2006 in my own party was painful. Even though, I can tell you, as much as a year before, my political consultants warned me that I would probably lose the primary and should think about running as an independent. But I had been a lifelong Democrat, and I refused to leave the party. Losing the primary in 2006 was painful. Winning the general election in 2006 was probably the most gratifying, satisfying day, night of my political career. So I didn’t emerge from that election angry. I emerged from that election feeling totally liberated politically as an independent.

People say, ‘Why did you support John McCain for president?’ I said, actually, truthfully, that he was the only candidate for president in either party who asked for my support. But there’s more to it than that. John and I are very close friends, and there is a role for friendship in politics as in life. Secondly, I felt at that time that he was just plain the best prepared to be the president we needed at that time. Enjoying the independence I had, as an independent, I did what I thought was best for the country at the time.

Even people who are loyal to you and respect you have characterized your speech at the 2008 GOP presidential convention as a low point and were dismayed by some comments you made about then-candidate Obama — that “eloquence is no substitute for a record,” for example — and for failing to push back on questions about whether Obama was a Muslim or a Marxist. Do you regret any of that, and do you think it may have undermined your own calls for civility?

Listen, when John asked me if I would speak at the convention, I figured, look, I’ve been speaking for him all over the country — I’d be a hypocrite if I don’t speak for him at the convention and try to explain why I really thought that my comments about Barack Obama, who I had great regard and affection for at that time. We were close and are again.

But when he first came into the Senate — incidentally, I believe that I went out of my way to discredit any of the thought that he was a Muslim at that time, because he isn’t and it didn’t make any sense. The good news is that after Sen. Obama was elected President Obama, he first did something very big and gracious, which is he urged Sen. [Harry] Reid and the Democratic caucus not to take away my seniority or my chairmanship as a result of my support of John McCain. And I’ve worked very closely with President Obama over these two years on a host of different matters, and I got a very gracious call from him the other night when I had decided not to run, and we’re going to work together in the years ahead as well.

Al Gore bitterly disappointed you when he endorsed your rival, Howard Dean, in the 2004 Democratic primary. Have you and former Vice President Gore ever spoken about his Dean endorsement — or anything else for that matter?

On the question of Al Gore: We’ve kept in touch. Of course I was disappointed when he endorsed Howard Dean in 2004, but that disappointment really has faded. …

His decision to ask me to be his running mate was a historic decision in the sense that he gave me the honor to be the first Jewish American to be nominated for national office. And it not only put his confidence in me — it put his confidence in the American people. And the fact is that we did get a half-million more votes than the Bush-Cheney ticket, and I think it says again what a wonderful, open country this is. I’ll never forget what Jesse Jackson said to me on the day that I got selected by Al Gore: He said, “You know, in America, when a barrier breaks for one group, the doors of opportunity are opened wider for everyone else.” Barack Obama actually said to me one day that he thought that the run that I made for vice president in 2000 really helped open the doors for him in 2008.

And none of that would have happened unless Al Gore had the confidence to give me that opportunity. So I will forever be grateful to Al Gore. I certainly consider him, and I believe he considers me, a good friend.

In your estimation, what has been your greatest legislative success in the Senate? And, conversely, your biggest disappointment?

One of the longest, most complicated legislative battles I’ve been involved in was the one to adopt the recommendations of the 9/11 Commission to reform our national security organizations after 9/11, and when we succeeded in that, that was a moment of real triumph and satisfaction.

The other one really was the recent one, and it all came together for a just cause, and it was the repeal of “don’t ask, don’t tell” [the ban on openly gay Americans in the military], which I’ve been against since it was adopted in ‘93. I voted against it. To me, it was not only important within itself — in other words, within the fact of what we were repealing — but it made a larger cultural statement about the openness and fairness of American society, so that was a thrilling moment for me.

It’s hard not to say that probably one of the biggest disappointments I’ve had was the failure of Congress and the federal government to take a leadership role in fighting climate change, which I think is a real and present danger to the United States and the entire world.

The Washington Post reported this week that you were “appalled” at McCain’s choice of Sarah Palin for a running mate. Is that true?

Not really. Look, it was John’s choice. Whatever feelings I had or have, I’m going to keep, out of respect for my friend John McCain, within myself.

Editor’s note: These interview excerpts have been edited for clarity. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.