Ritter, BillIn 1962, Denver Mayor Bill McNichols’ brother, Stephen, was the last incumbent Democratic governor to lose a re-election (via Wikipedia). State politics were different back then, but such details only make today’s announcement from Governor Bill Ritter more perplexing (via The Denver Post).

Ritter has confirmed he is not running for re-election in November, saying “taking care of his family” will instead become his priority.

Colorado House Speaker Terrance Carroll tells 9News in a statement he is confident the Dems can retain the governor’s office.

Ritter has been struggling politically. Internal polling numbers show Ritter down seven to nine points against the leading Republican candidate, former Congressman Scott McInnis. Ritter, a moderate, has faced problems battling the right, but he’s also had a “strained relationship with the Democratic base,” points out Politico, which highlights several confrontations with labor groups.

Republicans are taking some jabs, including Dick Wadhams, chairman of the state GOP. “Bill Ritter was literally the weakest incumbent in nearly 50 years, and his own party was unenthusiastic at best for his reelection,” Wadhams tells The Washington Post.

Speculation is swirling as to who might attempt to replace Ritter. Denver Post columnist Mike Littwin reels off a seemingly obvious list: Interior Secretary Ken Salazar, Denver Mayor John Hickenlooper, and perhaps even former state House Speaker Andrew Romanoff, who is now running for U.S. Senate.

Meanwhile, embattled Connecticut Senator Chris Dodd also held a press conference today to announce his resignation, adding another name to a growing list of Dems who are stepping aside (via WaPo).

One theory connecting Ritter to this group presumes that the Obama administration is clearing out its weakest links in order to seat stronger candidates for November.

McInnis spokesman Sean Duffy tells Westword it makes sense: “That celebrated night at Invesco Field [in 2008, when Barack Obama accepted the Democratic nomination for president] sure looks a lot different this morning, doesn’t it?” Duffy says. “And I don’t think they’re going to give back turf they’ve taken without a big fight—and one wouldn’t expect them to.”

During today’s press conference, however, Ritter said “nobody has ever pressured me” not to run.

Vanessa Martinez contributed to this post.