Sen. Joe Lieberman made it official Wednesday: He’s a lame duck and won’t run for re-election to a fifth term in the Senate.

At a Stamford, Conn., hotel which he said stands about on the spot where he lived in a coldwater flat for the first eight years of his life, the Connecticut independent and one-time Democrat said he wasn’t retiring because he might get beaten in 2012, which is what a number of people suspect.

No, Lieberman said. He would leave the Senate to do something else, though details were lacking on exactly what.

With his family flanking him, Lieberman said:

I have decided it is time to turn the page to a new chapter, and so I will not be a candidate for re-election to a fifth term in the U.S. Senate in 2012.  This was not an easy decision for me to make because I have loved serving in the Senate and I feel good about what I have accomplished.  But I know it is the right decision and, I must say, I am excited about beginning a new chapter of life with new opportunities.

I know that some people have said that if I ran for reelection, it would be a difficult campaign for me. But what else is new? It probably would be. I have run many difficult campaigns before—from my first one in 1970 against the incumbent Democratic State Senate Majority Leader, to my 1988 campaign against the incumbent Republican U.S. Senator, to my campaign for re-election to the Senate in 2006, at the height of the controversy over the Iraq war.  In all three of those elections most observers and pollsters thought I would not win.  But with a lot of help from Independents, Democrats and Republicans—including many of you here today—in each case I did win.

I’ve never shied from a good fight and I never will.

The reason I have decided not to run for re-election in 2012 is best expressed in the wise words from Ecclesiastes: “To everything there is a season, and a time to every purpose under Heaven.”  At the end of this term, I will have served 24 years in the U.S. Senate and 40 years in elective office. By my count, I have run at least 15 full-fledged political campaigns in Connecticut. For me, it is time for another season and another purpose under Heaven.

The speech was classic Lieberman, reflecting his well-known devotion to his religion — he’s an observant Jew — as well as his claim to being not easily classifiable as to political ideology.

To that latter point, he said:

Along the way, I have not always fit comfortably into conventional political boxes—Democrat or Republican, liberal or conservative. I have always thought that my first responsibility is not to serve a political party but to serve my constituents, my state, and my country, and then to work across party lines to make sure good things get done for them.

Now that he’s told us of his plans to end his Senate career himself, it’s safe to say that what he will likely most be remembered for is the way he antagonized so many in his own party. Lieberman clearly made many in his party angry, and they, in turn, angered him.

But Lieberman was a complicated figure and, as he would say, not easy to pigeonhole.

For instance, though he is generally conservative on defense issues, he was one of several lawmakers instrumental to the recent repeal of Don’t Ask, Don’t Tell, the law that banned gays and lesbians from serving openly in the U.S. military.

When the effort to repeal DADT faltered and appeared dead, it was Lieberman — with the help of Republican Sen. Susan Collins (R-ME) and Rep. Steny Hoyer (D-MD), who at the time was the House majority leader — who helped revive it in the Senate.

In recent years, voted with liberals between 50 percent and 60 percent of the time, voting to raise gas mileage standards for cars and to fund the expansion of the State Children’s Health Insurance Program.

Lieberman also had the vision that the nation needed a Homeland Security Department long before many others did.

It’s probably fair to say that Lieberman wasn’t as well known outside Connecticut before the late 1990s as he was after that.

In 1998, when President Bill Clinton was being tried in the Senate during the Lewinsky Scandal, Lieberman made a Senate speech that condemned the president, even though he ultimately voted against convicting the president. It was an action that won him few friends among Clintonistas and made some see him as sanctimonious.

But that moment also helped Vice President Al Gore choose Lieberman as his vice presidential running mate. It was one more way for Gore to distance himself from Clinton and to tie into Lieberman’s reputation for moral probity. It didn’t work out for the Gore-Lieberman ticket.

Lieberman made history as a vice presidential nominee, becoming the first Jewish American on the national ticket of one of the two major parties.

Lieberman later became the focus of Democratic wrath for supporting the Iraq War even after it became clear that President Bush misfired in his reasons for waging the war, that no weapons of mass destruction were found in Iraq.

Irate Democrats made sure that Lieberman lost the Democratic primary in 2006. But Lieberman survived that setback, running and winning as an independent.

Two years later, in what many Democrats viewed as an act of treachery, Lieberman not only endorsed the Republican presidential nominee, his friend Sen. John McCain of Arizona, but also spoke on McCain’s behalf at the Republican convention. After winning the White House, Obama advised fellow Democrats to hold “no grudges” against Lieberman, who was allowed to keep his prized chairmanship of the Homeland Security Committee.

During the course of the health-care debate, Lieberman increased the rift with many in his former party by flatly opposing the public option.

In announcing his retirement Lieberman only alluded to such running arguments with those in his former party. He took the opportunity in his speech Wednesday, a kind of valedictory, to say what he would prefer to be remembered for.

Some of the most satisfying moments of service I’ve had are the ones that usually don’t get public attention, when my staff and I have been able to provide support to one of you, a constituent in a moment of need, whether it was protecting a family from losing their home to foreclosure, helping the parents of a sick child get the health care they needed, or ensuring that a World War II veteran finally received the medals and recognition he was due for his service decades before.

I’m also grateful for what I’ve had the opportunity to accomplish in the Senate itself: what I’ve been able to do, for instance, to protect our environment—leading the fight against air and water pollution and climate change, cleaning up Long Island Sound, protecting the Connecticut River, and creating Connecticut’s first and only National Park site, Weir Farm.

I’m also proud of what I’ve been able to do for Connecticut businesses—helping them to keep and add jobs in our state, particularly in our defense industries, and to save Submarine Base New London.

And I’m proud of what I’ve been able to do to keep our country and people safe in a dangerous world—as a member of the Senate Armed Services Committee, supporting our troops and providing them with the best equipment possible—and in the years since the terrorist attack of 9/11/01, as Chairman or Ranking Member of the Senate’s new Homeland Security Committee, I’ve been at the center of Congressional efforts to strengthen our homeland defenses, including the creation of the Department of Homeland Security and the enactment of the recommendations of the bipartisan 9-11 Commission, which together are the most sweeping reforms of our national security institutions since the start of the Cold War.

By announcing his departure, Lieberman assures he won’t meet the fate of the man he replaced in the Senate, Lowell Weicker.

Weicker, a moderate Republican, was so detested by conservatives, including William F. Buckley Jr., that some even threw their support to Lieberman just to make sure Weicker was defeated.

The White House press office issued the following statement from President Obama:

“I want to congratulate Senator Joe Lieberman on an extraordinary career in public service.  Joe has spent four decades fighting for what he believes in on behalf of the people of Connecticut.  From cracking down on polluters and deadbeat dads as Connecticut’s Attorney General to his years of work defending our nation’s security on the Armed Services and Homeland Security Committees to his relentless efforts in recent months to repeal “Don’t Ask Don’t Tell”, his work has touched countless lives in his home state and across the country.  Even if we don’t always see eye to eye, I always know Joe is coming from a place of principle.  I know he will carry with him that integrity and dedication to his remaining work in the Senate and to whatever he chooses to do next.”

(This post has been revised since it was first posted.) Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.