WASHINGTON -- Jim Messina, who is leading the effort by Organizing For Action to press for tougher gun laws, has a problem: his old boss.

OFA, the offshoot of the Obama campaign now organized as a nonprofit organization, has made gun control its top priority, and Messina has been the public face of that effort. The president on Thursday pressed supporters to keep the pressure on by swarming congressional town halls during Congress' recess to drive the message home.

Democrats have largely rallied to the cause, but a major holdout is Montana Democratic Sen. Max Baucus, who's up for reelection in 2014 and who launched the career of Messina. Or, depending on whom you ask in the Senate, it's understood to have been the other way around.

"The relationship is much tighter, much closer than the typical staffer-senator relationship. In years past, whenever Senator Baucus got in the middle of a political brawl or a significant policy debate, Messina was never far behind," recalled one former senior Senate aide who knows both well. "The relationship counted for something, because I couldn't help but notice [OFA is] not running ads in Montana."

That might be for the best, tactically, said another former top Senate aide who worked closely with Baucus and Messina. "Jim knows better than anyone that trying to pressure his mentor Max Baucus in his home state on guns is not smart personally or politically."

Messina, when he worked with Baucus, was known to be able to speak for the senator. When President Barack Obama took office, Baucus recommended him for a high-level position. From that perch, Messina ran health care reform negotiations effectively out of Baucus' office. Baucus moved the legislation through his Finance Committee while picking up the vote of Republican Olympia Snowe of Maine, giving the bill the bipartisan sheen that Obama and Messina craved.

Messina is the Baucus whisperer. If anyone can reach out to Baucus on a tough issue like this, while still being mindful of Montana politics, it is him, said a Senate aide.

But that alliance hasn't been enough to move Baucus on guns. "I understand these are tough political votes ... but it's also the right thing to do, and I think there's a real political price to be paid for opposing something like a background check when over 90 percent of the country supports it," Messina said during an appearance on MSNBC Thursday. Obama has dubbed people who oppose the proposal "the 10 percent."

Implementing universal background checks is at the heart of the gun control legislation Senate Majority Leader Harry Reid (D-Nev.) plans to introduce after Easter recess.

Senate Democrats are expected to overwhelmingly support the bill -- except for a minority of red state Democrats that includes Baucus.

The Montana senator said he has no plans to back any new legislation aimed at curbing gun violence.

"I am focusing more on enforcement of current law," Baucus told Politico . "I am going home [on Saturday.] Ill talk to Montanans and see what my employers want."

A Baucus spokesperson indicated much of the same when asked by The Huffington Post if those comments meant the senator does not support any new legislation on background checks.

"Max has said he opposes the assault weapons ban. He voted against it in 2004 and would vote against it again," the spokesperson said in an email. "He will continue talking to Montanans before taking any votes on additional proposals, but in general Max has said we need to start by better enforcing the laws that are already on the books before passing new laws."

Baucus enjoys an A+ rating from the National Rifle Association.

A spokeswoman for Messina didn't immediately return a request for comment.

Universal background checks have tremendous support among the public, with recent polling showing that 88 percent of Americans believe firearms purchases at private sales and gun shows should be subject to a background check. The majority of gun owners are also on board, with 81 percent expressing their approval for universal background checks.

Mayors Against Illegal Guns, the pro-gun control advocacy group chaired by New York City Mayor Michael Bloomberg, found that 79 percent of Montana residents favor mandatory background checks.

The group noticeably left Baucus out of a $12 million ad blitz targeting senators on the fence about expanded background checks.

Obama stepped up the pressure on congressional lawmakers Thursday, delivering a speech flanked by 21 women impacted by gun violence.

"I ask every American to find out where your member of Congress stands on these ideas, " Obama said. "If they're not part of that 90 percent who agree that we should make it harder for a criminal or somebody with a severe mental illness to buy a gun, then you should ask them -- why not? Why are you part of the 10 percent?"

"There's absolutely no reason why we can't get this done," he added.