And just last week, Baucus called the implementation of Obama's health care law a "train wreck," even though he helped shepherd the legislation through Congress, That caused a tizzy among many Senate Republican officials, who speculated the senator was attempting to save his own reelection campaign by performing early damage control on a politically toxic issue.
But even if retirement talk has been off the public's radar, it's been something the senator has been considering, according to one former Baucus aide. A contributing factor, according to the source, was the septuagenarian was not eager to balance legislative fights, fundraisers and another tough reelection battle.
Although the senator's path to reelection was always going to be difficult in a state Mitt Romney won by double digits last year, he didn't appear as endangered as colleagues such as Landrieu in Louisiana, Mark Begich in Alaska, and Mark Pryor in Arkansas. He had yet to draw a first-tier challenger — only state Senate Majority Leader Corey Stapleton and state Rep. Champ Edmunds had declared they were running. Just last year, incumbent Sen. Jon Tester won reelection in Montana.
Baucus is the fourth consequential Democratic retirement this year, joining Sens. Tom Harkin of Iowa, Tim Johnson of South Dakota, and Jay Rockefeller of West Virginia. As with those previous retirements, his departure could give Republicans a golden opportunity to win a Senate seat and boost for their hopes of retaking the chamber.
But Democrats have been quick to suggest that former Gov. Brian Schweitzer, who left office this year, is interested in running. The popular former statewide official, who doesn't possess a potentially harmful voting record like Baucus has, might even be a stronger candidate than the incumbent.
"Democrats have had a great deal of electoral success in Montana over the last decade, and I am confident that will continue," Democratic Senatorial Campaign Committee Chairman Michael Bennet said in a statement. "Democrats built an unprecedented ground game in Montana in 2012 when Senator Tester was reelected, and we will continue to invest all the resources necessary to hold this seat."
Schweitzer, who won reelection as the state's governor in 2008 with more than 60 percent of the vote, fits the model of the kind of candidate Senate Democrats like to recruit — someone who can carve out the necessary independent image for Democrats to win in red states. He helped elect a Democratic successor, former state Attorney General Steve Bullock, into the governor's mansion last year.
Some Montana Democrats are also floating the name of Stephanie Schriock, the president of EMILY's List and a Montana native. The former chief of staff to Tester doesn't have the ideal background for the red-state race, but she would command a national fundraising base.
Elahe Izadi contributed contributed to this article