Democrat-turned-independent Sen. Joe Lieberman of Connecticut announced Wednesday he would retire from the Senate in 2012, ending a tenure that began in 1989.

Lieberman, Connecticut's state's former Attorney General who rose to become the Democratic Party's vice presidential nominee in 2000, spoke to reporters during a press conference and depicted himself as a victim of Washington's modern brand of partisan politics.

"Along the way, I have not always fit comfortably into conventional political boxes -- maybe you've noticed that -- Democrat or Republican, liberal or conservative," Lieberman said. "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."

A survey by the left-leaning Public Policy Polling (PPP), released in October, found that Lieberman was rather unpopular in his state, facing high disapproval ratings from Democrats, Republicans and independents, and dramatically trailing potential challengers from both parties.

"Two-thirds of those likely to cast their ballots this fall are looking forward to voting Lieberman out of office in the next election—including 70% of Democrats, 61% of Republicans, and 63% of independents—while only a quarter are committed to re-electing him," PPP noted.

But Lieberman insisted that his policy positions were guided by principles, comparing himself to Democratic President John F. Kennedy.

"The politics of President Kennedy -- patriotic service to country, support of civil rights and social justice, pro-growth economic and tax policies, and a strong national defense -- are still my politics," Lieberman said. "So maybe that means that JFK wouldn't fit into any of today's partisan political boxes neatly."

Lieberman infuriated liberals by breaking ranks to champion the Bush administration's foreign policies after the 9/11 attacks, most notably the war in Iraq, which led to his defeat in the 2006 Democratic primary. Instead of bowing out then, he ran and won the general election as an independent, but continued to caucus with Senate Democrats.

During his tenure, Lieberman served as chairman of the Senate's homeland security committee and briefly held a post on the governmental affairs committee.

This video is from the Associated Press, broadcast Jan. 19, 2010.