(USA TODAY) - President Obama is pitching the most ambitious gun control program in decades - but whether it becomes law or not remains to be seen.
While Obama said any action that can save one child's life is worth it, he and aides indicated that proposals to ban assault weapons, expand background checks, and restrict the capacity of gun magazines face big hurdles on Capitol Hill.
"This will be difficult," Obama said Wednesday at the White House. "There will be pundits and politicians and special interest lobbyists publicly warning of a tyrannical, all-out assault on liberty - not because that's true, but because they want to gin up fear or higher ratings or revenue for themselves."
Vice President Biden, who helped push through background checks and an assault weapons as a Delaware senator in 1993 and 1994, said he has "no illusions about what we're up against or how hard the task is in front of us."
The main reason: The Republicans control one branch of Congress, the U.S. House, and many of their members have sworn strong fidelity to Second Amendment gun rights.
Gun rights supporters sharply criticized the president's proposals as ineffective, unconstitutional, and politically motivated. Republican Party Chairman Reince Priebus said the plan amounts to "an executive power grab that may please his political base but will not solve the problems at hand."
The National Rifle Association, which has major influence on congressional Republicans, has declared all-out opposition to the president's gun proposals, saying that "attacking firearms and ignoring children is not a solution to the crisis we face as a nation." The NRA has stressed mental health issues, and called for more armed guards in schools.
A new assault weapons ban may be the toughest to achieve. After all, Congress refused to renew the old one when it expired in 2004.
Larry Pratt, executive director of the group Gun Owners of America, said "assault weapons" is the wrong term to use, and that these are "defensive weapons" that people are entitled to have to "defend themselves and their property." People are also entitled to have high capacity magazines, Pratt said.
At the White House, Obama said the combination of semi-automatic weapons and high-capacity magazines have enabled shooters to kill more people quicker, at venues ranging from the elementary school in Connecticut to a movie theater in Colorado.
"Weapons designed for the theater of war have no place in a movie theater," Obama said. "A majority of Americans agree with us on this."
Gun rights groups have also criticized proposals for "universal background checks" as a back door way of a national gun registration system that could lead to confiscation.
"You don't trust governments," Pratt said. "And it doesn't solve crimes."
Pratt said he would prefer to see Congress repeal laws creating gun-free school zones. As for Obama's plans, he said "we have a good chance" of beating them back.
Gun control advocates are more optimistic, but say there is a long way to go.
Kristen Rand, legislative director with the Violence Policy Center in Washington, D.C., said public opinion has been shifting in favor of gun control since the 2011 mass shooting at in Tucson and the July killings at a movie theater in Aurora, Colo.
Then came the Dec. 14 attack that killed 20 children and six adults at Sandy Hook Elementary School in Newtown, Conn.
"I've never seen this sort of sustained response," Rand said. "It's definitely changing the atmosphere."
People are concerned not only about mass shootings, but the "day-to-day gun violence in America," Rand said. Gun control supporters must also talk to people -- and their members of Congress -- about the extent to which assault weapons have virtually taken over the gun industry.
The fact that Obama has proposed a big package should help in Congress, Rand said, though she declined to give odds on specific items.
"It's a process," she said. "We're not going to predict right now where the votes might shake out."
Obama, Biden and their aides said they believe the political dynamic has changed on guns -- especially after Newtown.
Citing opinion polls showing more sympathy to gun control proposals, Obama called on voters to pressure members of Congress, including those whose districts have a strong tradition of gun ownership.
"This will not happen unless the American people demand it," Obama said.