The Hartford Courant’s website is reporting that Senator Joseph Lieberman is poised to announce that he won’t run for re-election in 2012. Lieberman will announce his 2012 plans Wednesday in his hometown of Stamford, at an event where he will be surrounded by longtime supporters, adding to speculation that he will speak of the end of his political career in the place where he grew up. The decision not to wait is being linked to the announcement by Susan Bysiewicz, a popular Democrat who has served as Connecticut’s secretary of state and was ruled off the ballot last year for state attorney general by a technicality, that she will run for Lieberman’s seat.

The Courant speculates that the reason Lieberman is not waiting until later in the election cycle to pull out is because he wants to make his statement “while there’s still speculation that he could still win if he chose to run.” Maybe. But the only reason Lieberman is bailing now is because he knows he has no chance to win in 2012.

I wrote last month that indications that Linda McMahon was going to make another try for the Senate in 2012 made a repeat of Lieberman’s 2006 win as an independent virtually impossible because he would need the GOP to more or less not show up the way they did in that race. In response, some readers contended that if Connecticut Democrats nominated an unpopular hard-core left-winger, Lieberman could still squeak through. But given that the Democratic field is already shaping up as one populated by highly electable candidates like Bysiewicz and Rep. Joseph Courtney, who has also indicated interest, this is an extremely unlikely scenario. Sam Stein at the Huffington Post reports that Patty Murray, the new chair of the Democratic Senatorial Campaign Committee, has told Lieberman that her group might back him in a primary if he returned to the Democrats. But that seems like an empty promise, since even more Democrats are angry with Lieberman today than they were when he lost his party’s primary in 2006. With party activists in both parties dead set against Lieberman, he has no chance to win either party’s nomination, and if faced with two strong opponents rather than just one, which now seems to be a given, he has no chance to win.

Lieberman has had a remarkable run in elected office. He started out as a stereotypical liberal Democrat when he first ran for the State Senate from New Haven (the young Bill Clinton was a campaign volunteer). Lieberman later became state attorney general and then turned conventional wisdom on its head by running to the right of liberal Republican Lowell Weicker in 1988. Once in office, he became enormously popular, striking a balance between conventionally liberal economic stands while also articulating centrist stands on foreign policy and social issues. Lieberman came within a few hanging chads of becoming vice president in 2000, but the moral tone and foreign policy stands that helped win him that nomination would ultimately alienate him from fellow Democrats. His principled support for the Iraq war was the turning point for him, and it ultimately ensured that he would be the last of the Scoop Jackson Democrats in the U.S. Senate. While he wasn’t always right on all the issues, his is a voice that would, come 2013, be greatly missed.