(CNN) -- When a set of recommendations to reduce gun violence hits President Barack Obama's desk on Tuesday, it will trigger a new stage in a decisive political battle consuming Washington. And it will show just how much America may have changed in the wake of last month's massacre in Newtown, Connecticut.
The proposals from a White House task force may include some with broad support on issues involving mental health. But one of the most intense flashpoints is already known: The group, overseen by Vice President Joe Biden, is expected to support reinstating an assault weapons ban.
"I would say that the likelihood is they will not be able to get an assault weapons ban through this Congress," National Rifle Association President David Keene said Sunday.
But the powerful gun rights lobbying group is gearing up for a fight -- which, CNN has learned, will include an ad campaign.
"When a president takes all the power of his office and is willing to expend political capital, you don't want to make predictions," Keene said on "State of the Union."
Keene said he also does not believe Congress will pass a ban on high-capacity magazines.
The NRA argues that such bans won't help stop gun violence, and that they infringe on Second Amendment rights.
But Sen. Chris Murphy, D-Connecticut, said the NRA's prediction is wrong. "I think that this issue is going to continue to move," he told "State of the Union," speaking from Newtown.
Biden told reporters last week, amid meetings with a wide array of groups, that he had never heard so much support for "the need to do something about high-capacity magazines."
Sen. Dianne Feinstein, who is pushing a ban similar to one that expired in 2004, has said she believes it will make it through Congress.
"All of the things that society regulates, but we can't touch guns? That's wrong," Feinstein said in December after 27 people, including 20 children at Sandy Hook Elementary School, were killed in Newtown by a gunman who then shot himself to death.
Numerous mass shootings have involved high-capacity weapons.
Obama set up the task force and instructed the group to have proposals by the end of January. Biden said last week he will have a set of recommendations ready for the president by Tuesday.
While the NRA, with 4.2 million members, holds a great deal of sway, it faces a country deeply concerned about the kinds of weapons that have been used in numerous mass killings. It's also facing a new foe: a political action committee created by former Rep. Gabrielle Giffords and her husband, Mark Kelly.
Giffords was shot in the head in a mass shooting two years ago that killed six people.
"With Americans for Responsible Solutions engaging millions of people about ways to reduce gun violence and funding political activity nationwide, legislators will no longer have reason to fear the gun lobby," the two vowed in a USA Today op-ed last week.
Obama made clear Saturday that he's ready for a fight over how to respond to gun violence.
In his weekly radio address, he gave a list of challenges ahead, including protecting "our children from the horrors of gun violence."
"These, too, will be difficult missions for America. But they must be met," he said.
The Obama administration will try to pass an assault weapons ban, an administration official said Friday.
Sen. Joe Manchin, D-West Virginia, told CNN he believes that a ban on assault weapons alone, "in the political reality that we have today, will not go anywhere." A strong advocate for Second Amendment rights with an "A" rating from the NRA, he has expressed openness to changing laws -- but argues that other aspects of society should change as well. "It has to be a comprehensive approach," he argued Sunday on "State of the Union."
Sen. Chuck Schumer, D-New York, called Sunday on the nation's largest gun retailers to "participate in a temporary moratorium on selling assault-style rifles until Congress has considered legislation to reduce gun violence," his office said in a statement.
"Since the Sandy Hook massacre, sales of assault-style rifles have skyrocketed, and are poised to grow even further during an upcoming 'Gun Appreciation Day' organized by extreme pro-gun activists," the statement said.
The group behind the event, scheduled for January 19, uses its website to encourage Americans to "go to your local gun store, gun range or gun show with your Constitution, American flags and your 'Hands off my Guns' sign to send a loud and clear message."
Dick's Sporting Goods, one of the largest sporting goods retailers, suspended sales of certain semi-automatic rifles nationwide after the Newtown massacure.
Another likely point of contention between gun rights activists and those supporting stricter gun control is a call for universal background checks.
Biden has said several groups that his task force met with support such checks for all gun buyers, including those who purchase through private sales.
Keene has also told CNN that he does not support instituting background checks for purchases at gun shows.
He said Sunday the NRA does support the idea that people who are ruled mentally incompetent should be listed as not allowed to purchase firearms.
In the interview Sunday, Keene complained that Biden's panel didn't really listen to what the NRA had to say.
Despite promises that the task force had not reached conclusions before hearing from all sides, "the conclusions were reached," he argued. "We suspected all they wanted to be able to do was to say he had talked to us, and now they were going to go forward to do what they wanted to do."
Another question facing Biden's panel is how to tackle images of shootings in entertainment.
His task force met with leaders of the the film, TV, and video game industries.
It's unknown what the task force may suggest as a response to what Obama has described as a culture that often "glorifies guns and violence."
Meanwhile, across the country, Americans of all stripes are debating the issue -- in person, in town hall meetings, and in social media.