Back during the Clinton era, the Democrat faced a choice: support an assault weapons ban urged by a president from his own party and risk angering constituents who cherish their gun rights, or buck his party. He chose the ban, and nearly lost his Senate seat.

Now, as he begins his campaign for a seventh term, Baucus faces the question again. For weeks, gun foes have sought assurances he would oppose the assault weapons ban. But it was only this past week he said he would oppose it.

That decision alone doesn't settle the issue for his re-election campaign. His opponents are watching closely, eager to pounce as he navigates a series of other gun control proposals, including an expected call for universal background checks.

Baucus' predicament is one that a group of Democrats like him in the West and South are facing. They hail from predominantly rural regions of the country where the Second Amendment is cherished and where Republicans routinely win in presidential elections.

From Montana to Louisiana, these anxious voters have made at least six Democratic senators a little uneasy heading into next year's election season. Both sides are aware that gun-owners' rights are taking shape as a campaign issue that could shift the balance of power in the U.S. Senate.

"Make no mistake — it is a very delicate dance for rural state Democrats," said Barrett Kaiser, a Democratic political consultant.

"I would be stunned if the Montana congressional delegation said anything but 'hell no' to gun control measures," he added.

Part of the concern comes from a proposal by Sen. Dianne Feinstein, D-Calif., that would ban assault weapons and high-capacity clips. The plan is a response to calls for new gun restrictions from President Barack Obama in the aftermath of the shooting rampage at a Connecticut elementary school.

Gun control is a top-agenda item for many Democrats, and they'll need all the votes they can to push changes.

Baucus knows, though, that a gun control vote "opens the door for whoever challenges him, because Montanans do not want the federal government restricting guns. That is clear as day," said Republican state Rep. Scott Reichner, who was Mitt Romney's campaign chairman in Montana.

"It would be a monumental mistake on his part" to support federal gun control legislation, Reichner said.

Gun rights carry sway in Montana. The state Department of Fish, Wildlife and Parks says Montana "boasts more hunters per capita than any other state in the nation." State lawmakers have been discussing measures to expand gun rights. And a pro-gun group, the Montana Shooting Sports Association, has set up a website that is updated with Baucus' public statements on gun policy.

Other Democratic senators that Republicans are watching closely include Mark Begich of Alaska, Kay Hagan of North Carolina, Tim Johnson of South Dakota, Mary Landrieu of Louisiana and Mark Pryor of Arkansas.

Democrats control the Senate, but if Republicans pick off these seats they could take the chamber.

Pryor already has said he won't support an assault weapons ban, and the measure is unlikely to clear the Senate. Gun activists still worry that other restrictions they oppose are in the works.

"I don't think the assault rifle ban, the semi-auto ban, has been the real objective," said Gary Marbut of the Montana Shooting Sports Association. "I think that is where the rubber meets the road, federal gun registration."

The gun rights crowd considers mandatory registration as an unconstitutional overreach of federal authority and the close attention paid to all discussions on the topic show how carefully Baucus and others must tread.

Baucus would appear to be a shoo-in for re-election. He's the third most senior U.S. senator and the chairman of the Finance Committee, which lets him prioritize many Montana projects.

He's also a consummate dealmaker who routinely collects endorsements from Republican-allied groups like the U.S. Chamber of Commerce. And he's worked hard over the years to become the only Senate Democrat with an A-plus rating from the National Rifle Association.

But one wrong gun vote could energize his opposition.

Though Baucus specifically rejected the assault rifle ban, he stopped short of mentioning expanded background checks by name. Baucus indicated he prefers the focus was elsewhere.

"Instead of focusing on new laws, Max believes the first step should be effectively enforcing the laws already on the books," Baucus spokeswoman Jennifer Donohue said Thursday.

The entire debate represents a potential replay of the most difficult fight of his career, when Baucus voted for the 1993 Brady Bill that established background checks and the original 1994 ban on assault rifles and high-capacity clips.

Those votes led to the closest election in four decades of politics for Baucus, a narrow victory in a bitter campaign against Republican Denny Rehberg.

The other Democratic senators in rural states could find themselves in similar fights and have been cagey over the issue. Most have taken a wait-and-see approach.

The NRA last month launched an advertising campaign aimed squarely at this group, sending a strong message. The organization did not return a call seeking comment.

Democratic political operatives say the NRA could be overplaying its hand this time, arguing some sportsmen may be willing to listen to moderate proposals.

Still, Baucus and his colleagues aren't likely to take risks and by next year's election, he and others could seek to turn the issue to their advantage by using a pro-gun stance to appeal to conservative and libertarian-minded voters.

"Why wouldn't he want to talk about guns?" said Montana State University political scientist David Parker. "Sen. Baucus is as about as middle of the road as they get in the United States Senate. What he doesn't want to do is have himself painted as a national Democrat or as an Obama Democrat."