"The best known Democrat, who has expressed interest in a Senate run in 2010, is (former Secretary of State) Susan Bysiewicz," said McLean. But Bysiewicz faced heavy criticism over voting mishaps and her handling of the 2010 gubernatorial election.
Meanwhile, over on the Republican side, the names of a couple of 2010 Senate contenders -- Linda McMahon and former Rep. Rob Simmons -- remain in the mix, ensuring a crowded field of potential candidates from both parties will be keeping an eye out for Lieberman's decision.
"The Democrats generally would be hurt by a Lieberman retirement and a McMahon nomination," said McLean.
Sen. Jim Webb (D-Va.)
As Webb ponders whether to seek a second term, former Sen. George Allen (R) looks like a candidate eying a rematch of the extremely close 2006 contest.
Webb suggested in a December interview that a decision would probably come during the first quarter of this year.
The Democratic bench is thin in Virginia, and Democratic National Committee Chair Tim Kaine is widely viewed as the best possible Democratic nominee if Webb opts against a run. But over the weekend, Kaine said that he intends to stay on as head of the DNC for another two years.
Sen. Kay Bailey Hutchison (R-Texas)
A December Washington fundraiser set off a new round of speculation over a possible 2012 Hutchison re-election campaign.
In this case, the focus is much more on the primary field than on the general election, as a Hutchison would likely be met with opposition from Tea Party-backed candidates who have been waiting in the wings for their chance at a Senate bid.
Perhaps the most eager onlooker is Dallas Mayor Tom Leppert, a Hutchison ally with an eye on a Senate run, but an apparent reluctance to run against Hutchison in a primary.
Leppert has a re-election decision of his own to make and a decision not to run for another term as mayor would likely be perceived as a move toward a Senate campaign.
Sen. Jeff Bingaman (D-N.M.)
News this week that former Rep. Heather Wilson (R-N.M.) is considering a run at Bingaman's seat reignited buzz that Republicans could land a top notch candidate for the race. Wilson recently completed chairing Gov. Susana Martinez's (R) transition.
Bingaman has yet to definitively say the he is running in 2012, but in a recent interview with radio reporters, said that he's indicated to people that he would make a decision in "late February or March."
"I think the anticipation is that Jeff is going to run," said New Mexico politics blogger Joe Monahan, who added that he anticipated a decision from Wilson would come in three or four months.
While Wilson has said that she does not have a timetable for a decision, former congressional candidate Greg Sowards (R) has already announced he is in the race, though he is considered to be a minor candidate.
While Republicans performed well in New Mexico at various levels during the 2010 election, Democrats appear confident. All indications are that Bingaman will run again, and if he does, Democratic chances at holding the seat appear to be very good. But if for any reason he bows out and Wilson decides to run, the situation could change.