The panel has a long tradition of bipartisanship, but Baucus ascended to power in an era of increasing partisanship in Congress.

Many Democrats were unhappy when he worked with Republicans to enact the tax cuts that President George W. Bush won in 2001. And then again in 2004 when Congress pushed through a GOP plan to create a new prescription drug benefit under Medicare, a measure that most Democrats opposed as a giveaway to the large drug companies.

Baucus stood with fellow Democrats in 2005 when Bush proposed legislation to partially privatize Social Security, an epic battle that ended in defeat for the president's effort.

He played a central role in the enactment of Obama's watershed health care legislation in 2010, although some inside his party complained that precious momentum was lost while he spent months on bipartisan negotiations that ultimately proved fruitless.

More recently, Baucus has expressed opposition to Democratic proposals to use an overhaul of the tax code as a means of raising additional revenue. He was one of four members of his party to oppose the budget the leadership brought to the floor with a requirement to that effect.

On other issues large and small, Baucus' voting record reflected his rural state.

Most recently, he voted against legislation that Obama backed to expand background checks for gun purchasers.

During the debate on the budget, he was the only Democrat to vote for a proposal to reopen White House tours. Most members of his party viewed the GOP measure as an attempt to embarrass Obama, but it would also have meant more money for clearing snow from the entrances to Yellowstone National Park, a portion of which is in Montana.

For more than a decade, Baucus has sought federal assistance for the residents of Libby, Mont., where asbestos contamination from a vermiculite mine has been linked to deaths and illnesses.

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