WASHINGTON — President Barack Obama announced a sweeping slate of new gun control proposals Wednesday designed to curb mass violence.

The plan was described as a major initiative by advocates on both sides of the debate. But in many respects, it is limited in scope, reflecting the political constraints of an issue that divides the country, as well as the power of the gun lobby.

“While there is no law or set of laws that can prevent every senseless act of violence completely, no piece of legislation that will prevent every tragedy, every act of evil, if there is even one thing we can do to reduce this violence, if there is even one life that can be saved, then we’ve got an obligation to try,” Obama said, standing near four young children who had written him letters after the Newtown, Conn., shooting.

The National Rifle Association has made clear that it was ready for a fight. Even before the president’s speech, it broadcast a provocative video calling Obama an “elitist hypocrite” for opposing more armed guards in schools while his daughters had Secret Service protection.

Inside, we take a closer look at the proposals that will require action from Congress and offer an educated guess of how likely they are to pass, based on polling and what lawmakers have said:

A ban on assault weapons and high-capacity ammunition magazines

Sen. Dianne Feinstein, D-Calif., is set to introduce such a ban in the Senate soon, but its odds of passage don’t look that promising right now. Both Senate Majority Leader Harry Reid, D-Nev., and House Minority Whip Steny Hoyer, D-Md., have expressed doubts, while conservative Democrats the president will need on his side also have offered reservations. The National Rifle Association opposes such a ban.

What polling shows: A Washington Post-ABC News poll released Monday showed 58 percent of adults and 59 percent of registered voters support a nationwide ban on the sale of assault weapons. But the issue divides Republicans and Democrats, something that especially matters in the GOP-controlled House, where many Republicans represent safe GOP districts that leave them more vulnerable to primary threats than general election challenges.

Odds of passage: Less than 50 percent

Requiring universal background checks in gun sales

Compared with an assault weapons ban, there is greater overall consensus around the issue of strengthening background checks by requiring them in firearm sales at gun shows and in other private transactions, to end the so-called “gun show loophole.”

What polling shows: About 88 percent of Americans said they support a law requiring background checks in sales at gun shows, according to the Washington Post-ABC News poll, including 89 percent of Republicans.

Odds of passage: 75 percent or better

Confirming B. Todd Jones as director of the Bureau of Alcohol, Tobacco, Firearms and Explosives

Among the steps Obama is taking by executive action is the nomination of Jones, currently the agency’s acting director, to head the agency, which has not had a permanent head in six years. The Senate would have to confirm Jones.

What polling shows: There is no recent polling on Jones.

Odds of confirmation: Very good, considering that there are no obvious reasons to hold it up. If concerns are raised, then the odds will be lowered.

Enhancing school safety

The Obama administration is proposing enhancing the physical security of schools and better preparing them to respond to outbreaks of mass violence. The administration’s proposal includes a call to put as many as 1,000 trained police officers and school counselors on the job. The administration notes that not every school will want the additional resources and the choice will be left to them. It is also calling on Congress to provide $30 million in one-time grants to states to help school districts shore up emergency management plans.

What polling shows: Overall, few Americans seem to disagree with the idea that school safety must be beefed up. The differences arise when it comes to the specifics. The Washington Post-ABC News poll showed, for example, that most support putting armed guards in every school — which is the idea the NRA has put forth. To be clear, the administration does not want to mandate school security; it is leaving choices up to the schools. The administration is calling for more funding for emergency management.

Odds of passage: Very good

McClatchy Newspapers and The New York Times News Service contributed.