Whatever you think of him, the career of Sen. Joseph I. Lieberman will go down as one of the most fascinating in the long history of that exclusive institution. His four-term, 24-year Senate career will end with the close of the lame-duck session.

His initial election to the Senate in 1988 came at the expense of three-term incumbent Sen. Lowell P. Weicker Jr. Then attorney general, Sen. Lieberman was in large part able to squeak out a victory by appealing to Connecticut conservatives who considered Sen. Weicker a traitor to the Republican Party because of his frequent support of traditionally liberal policies. Many Democrats would later come to view Sen. Lieberman the same way for his conservative leanings.

In office, Sen. Lieberman became an important cog in the coalition of moderate "New Democrats" who in the 1990s worked with President Clinton to move the party to the center, approving free trade agreements despite labor opposition, passing welfare reform in the face of progressive resistance, and bringing the budget into balance.

In 2000 President Clinton's vice president, Al Gore, seeking the presidency, chose Sen. Lieberman as his running mate, convinced that the Connecticut senator could help pick up the centrist vote critical to victory. The choice was historic, making Sen. Lieberman the first Jewish-American nominated by a major political party for national office. Vice President Gore saw an immediate jump in the polls. The Democratic ticket would ultimately receive 500,000 more votes, but lose to President George Bush and his GOP running mate, Dick Cheney, by four electoral votes in the controversial election.

Six years later Sen. Lieberman abandoned the party, refusing to support Democratic nominee Ned Lamont after Mr. Lamont, a liberal anti-war candidate critical of Sen. Lieberman's ardent support of the Iraq invasion, defeated him in the party primary. Sen. Lieberman would win re-election running under the Connecticut for Lieberman banner.

In 2008, despite having continued to caucus with Senate Democrats, Sen. Lieberman backed Republican presidential candidate Sen. John McCain, including speaking at the GOP convention, and received serious consideration as Sen. McCain's running mate.

So many twists and turns.

Yet to the senator's credit there was a consistency, a belief that the ability to govern effectively is found at the political center and a conviction that the United States must pursue an aggressive foreign policy.

In his farewell speech on the Senate floor Wednesday, Sen. Lieberman decried the rigid ideologies that stand in the way of cooperation.

"Today 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. It's the partisan polarization of our politics which prevents us from making the principled compromises on which progress in a Democracy depends," said Sen. Lieberman.

As chairman of the Homeland Security committee, he had hoped that passage of a cybersecurity bill, requiring cooperation among businesses and with the government to improve computer defenses against terrorist attacks on critical infrastructure, would place a coda on his Senate career. Unfortunately, it too fell victim to the political dysfunction in Washington.

Yet Sen. Lieberman's participation in important victories were many, and show he could never be ideologically pigeonholed. They include passage of the Clean Air Act in 1990, backing the U.S. involvement that stopped the genocide in the Balkans, creation of the Department of Homeland Security and, most recently, authoring and guiding into law the repeal of the military's "don't ask, don't tell" policy.

If there is one issue on which we strongly parted ways with the senator it was his fervent and seemingly unquestioning support of the Bush administration's decision to invade Iraq based on evidence that was dubious from the start and much of which proved false. While use of U.S. military force is at times critical, Sen. Lieberman was far too hawkish, particularly in his latter years, when it came to expending Americans lives and treasure abroad.

But while we disagreed, we trusted that Sen. Lieberman was doing what he thought was right and not what was simply politically expedient. We leave it to Sen. Lieberman to explain to the senators who will follow him why love of country, not devotion to party or ideology, must guide them if they want to accomplish great things.

"It means ultimately putting the interests of the country and constituents ahead of the dictates of party and ideology," said the senator in his farewell remarks. "And that is what is desperately needed … to solve our national problems and address our biggest challenges before they become crises or catastrophes."