Some pols are more or less faithful party-men who stray on occasion during challenging electoral cycles. Baucus, by contrast, has amassed a remarkably consistent record of working at cross-purposes with the rest of his party whether politics in Montana have demanded it or not.
He voted for the Bush Tax Cuts in 2001; then after securing re-election, and against the will of Democratic leadership, supported a Medicare prescription drug benefit that routed tax payer money through private insurers. He spent months and months behind closed doors with GOP lawmakers in 2009 in a futile search for bipartisan support for what became the Affordable Care Act. That quixotic effort dragged on well past the point at which party leaders believed it might pay off, and it delayed legislative action for so long that the bill nearly died when Democrats lost Ted Kennedy's seat to Scott Brown in early 2010.
His biggest contribution to ACA was to help build industry support for the process by cutting secret deals with pharmaceutical manufacturers and other powerful stakeholders, some of which may have been necessary to pass the bill, but which nevertheless came at the expense of beneficiaries and taxpayers.
In late 2010, Baucus voted against the DREAM Act.
A key exception to this track record is his long history of bucking GOP attempts to slash and privatize popular social insurance programs like Medicare and Social Security. But viewed through the prism of his broader approach to politics, this seems more an idiosyncratic instance of liberal priorities lining up with Baucus' venal decision making, than an expression of genuine commitment to the legacy of the New Deal and Great Society.
By contrast, his recent votes against gun legislation and the Democratic budget are vintage Baucus. One can argue that this sort of "independent streak" might protect Montana Democratic candidates in the abstract. But polling on the specifics doesn't really back up the view that Baucus needed to buck his party on these measures to remain viable. Which helps explain why Baucus' fellow Montanan Jon Tester (whom, I should note as a caveat won't be in cycle again until 2018) voted 'yes' on both occasions.
Fortunately in Baucus case there's almost no need to resort to electoral heuristics to explain his recent actions. He has a well-earned A+ rating from the NRA to explain his opposition to even modest gun control measures. And this year's Democratic budget undermines the sovereignty of his prized Finance Committee chairmanship, a position from which he's privately negotiating tax reform legislation with his House GOP counterpart, without regard to his party's commitment to increase federal revenue.
Again, none of this excludes the possibility that Baucus took these and other votes with his re-election in mind as well. But assuming that winning in 2014 has been his only beacon is actually giving him too much credit.