Sen. Joe Lieberman (I/D-CT) announced today he would not run for reelection in 2012.

After 23 years in the U.S. Senate, Joe Lieberman (I/D-CT), the one-time Democratic vice-presidential nominee, announced, as expected, that he would not seek reelection in 2012.

"I have decided that it's time to turn the page to a new chapter," Lieberman told a room of supporters gathered in a Stamford, Conn., hotel ballroom for the announcement. He added, "That was not an easy decision for me to make, because I have loved serving in the U.S. Senate. But I know it's the right decision."

During the height of the Iraq war in 2006, Lieberman, a defense hawk who supported the war, lost a primary to liberal Ned Lamont. But Lieberman switched to independent and won the general election in a three-way race. Lieberman then went on to endorse John McCain, the Republican nominee for president in 2008 over Democrat Barack Obama. Lieberman's poll numbers have suffered in Connecticut and he would have been in a precarious position if he ran for reelection. But that's not why he's retiring, Lieberman said.

"I have never shied from a good fight," Lieberman said, "and I never will."

Lieberman made reference to his politics and the complications he's had with his former party, with which he still caucuses.

"J.F.K. wouldn't fit neatly in today's partisan political boxes either," Lieberman said.

He made only fleeting reference to his 2000 run as the Democratic Party's vice-presidential nominee and failed 2004 presidential run.

He said he's run 15 "full-fledged campaigns" ... "not counting the national campaigns I was involved in."

Lieberman is the third senator to announce he would not seek reelection in 2012 and the second that caucuses with Democrats. Kent Conrad (D-ND) and Kay Bailey Hutchison (R-TX) are the others.