In politics, it seems you’re only as good—or as bad—as your last term and your last poll. That’s the lesson Connecticut senator Joe Lieberman is learning today, if yesterday’s reports on the then-impending announcement of his retirement are anything to go by. In the papers and on the blogs, Lieberman—in office since 1989—is presented a man defined from 2006 on, and by his declining popularity among his constituents. And his Democratic colleagues? Well, if they weren’t quite popping open the bubbly upon hearing the news, they were certainly putting it on ice. With likely Independent Lieberman out, there will be no pesky three-way vote split to advantage the GOP.

David M. Halbfinger and Raymond Hernandez’s front-page story in the Times today briefly glosses the fall-from-grace bio that led to this Lieberman we’re seeing all over the press today.

Connecticut voters once embraced Mr. Lieberman, the son of a liquor store owner who entered politics as a reform-minded Democrat in 1970, for his folksy ways and his common-sense approach to issues. But he repeatedly broke with his party during the past decade, and the political climate in the state had grown increasingly unwelcoming to him.

Supporting the Iraq war and John McCain will do that.

Referring to Mr. Lieberman’s plan to forgo re-election, Bill Curry, a prominent Democrat who served with Mr. Lieberman in the State Senate, said, “It’s the first thing he’s done in 10 years to make Connecticut Democrats completely happy.”

The Times also gave voice to just how unsurprising Lieberman’s announcement was, given his electoral prospects in 2012.

Rivals were already signaling they believed Mr. Lieberman was vulnerable; even before the news emerged on Tuesday, the Democrat Susan Bysiewicz, a former secretary of state in Hartford, had said she would run for the seat. Other possible contenders include Representatives Christopher S. Murphy, a popular three-term Democrat whose district includes Danbury and Waterbury, and Joseph Courtney, whose district includes New London.

The Hartford Courant reported:

A couple of active Democrats said they think the timing of the event, and the tone of the behind-the-scenes conversations, indicate that Lieberman wants to announce that he’s not running while there’s still speculation that he could still win if he chose to run. In other words, they said, he can pull out of the 2012 race now—before being battered by continual announcements of polls that show him sinking ever farther in his prospects.

Why so unpopular? Well, as Ezra Klein at The Washington Post puts it, for Democrats, Lieberman was the “best of friends, and also the worst.”

Lieberman’s behavior during the debate was often erratic and seemingly unprincipled. Among other things, he skipped the meetings where Democrats were trying to work out a compromise on the public option, and then he killed the Medicare buy-in proposal they’d developed—despite endorsing that exact proposal months before. In doing so, he doomed a great piece of policy, and by doing it at the last minute, endangered the rest of the bill, too. But the reality is that the legislation simply wouldn’t have passed without his vote. And after extracting his pound of flesh, he voted “aye.”

Slate’s David Weigel had his own spin on the decision, describing Lieberman’s move as “part graceful exit, part hit-the-road-before-they-burn-my-house-down.”

We can give the man some time to explain why he’s doing this, but let’s not lose sight of the obvious: He was going to lose if he ran. One of the last polls on a potential 2012 race, an October 2010 survey by Public Policy Polling, gave Lieberman an abysmal 31 percent approval rating. Twenty-four percent of voters said they’d re-elect him, to 66 percent who said they wanted to vote for someone else. In trial heats, Lieberman came in third in potential three-way contests; he lost by double digits to possible Democratic opponents.

… Lieberman turned everybody off and broke a series of promises. If you were a Democrat who supported him, you heard him promise to endorse the party’s 2008 presidential candidate, then you watched him endorse John McCain. If you were a Republican who supported him, you heard him say he couldn’t vote for the health care bill in December 2009, because of the Medicare buy-in. You might have even waved pro-Lieberman signs, as some people I met at a Tea Party rally in D.C. did at that time. Then you watched him cave once the buy-in came out.

Joel Meares is a former CJR assistant editor.