WASHINGTON – President Obama on Wednesday unveiled the most comprehensive federal gun-control plan in decades, but even some of his supporters tacitly acknowledged that major parts of what he is proposing are unlikely to make it into law.

While Obama called for a renewed federal ban on assault weapons and high-capacity ammunition magazines, congressional sources said that those ideas face stiff opposition, even from many rural-state Democrats.

More realistic, they said, was Obama’s proposal for universal background checks for all gun buyers, as well as his adoption of a long-standing proposal by Sen. Kirsten E. Gillibrand, D-N.Y., to make gun trafficking a felony.

“If you look at the combination of likelihood of passage and effectiveness of curbing gun crime, universal background checks is at the sweet spot,” said Sen. Charles E. Schumer, D-N.Y. “We’re glad the president put such emphasis on it, and we look forward to working with him on this and other proposals to make our nation safer from the scourge of gun violence.”

Meanwhile, Gillibrand said: “By cracking down on illegal gun traffickers and their vast criminal networks, we can stop the flow of illegal guns and reduce the violence that plagues too many communities around New York and across the country.”

However, even those proposals are expected to face strong opposition from the National Rifle Association, which, in a statement, chided the president for ignoring its plan to put armed police officers in every school.

“Attacking firearms and ignoring children is not a solution to the crisis we face as a nation,” the NRA statement said. “Only honest, law-abiding gun owners will be affected, and our children will remain vulnerable to the inevitability of more tragedy.”

While issuing 23 executive orders toughening enforcement of current laws, Obama also proposed several major changes that would require legislation, such as:

• An assault weapons ban that’s more comprehensive than the one that was in effect for a decade before its 2004 expiration.

• A ban on ammunition magazines of more than 10 rounds, as well as a ban on armor-piercing bullets.

• Eliminating a loophole in the law that allows people to buy guns without a background check at gun shows across the country.

• A proposal to make gun trafficking a felony.

• About $500 million in addition federal spending to train police officers and teachers about gun violence, to hire school psychologists and social workers, to conduct research on violent video games and media images and to bolster mental health programs.

“The most important changes we can make depend on congressional action,” the president acknowledged.

Obama outlined his plan at an emotional White House event. Behind him were four children who had written letters to the president, pleading for action.

Before him sat an audience filled with people who had lost loved ones to gun violence, most notably the families of children who were killed in the Sandy Hook Elementary School massacre in Newtown, Conn.

In detailing his plan, Obama implicitly acknowledged the difficult political fight ahead.

“If there’s even one thing we can do to reduce this violence, if there’s even one life that can be saved, then we’ve got an obligation to try,” he said.

The legislative effort on gun control is likely to start in the Senate, which, congressional sources said, is likely to take it up piecemeal rather than in one comprehensive bill. That’s because an assault weapons ban could be a poison pill that could kill the entire package if everything were wrapped into one bill.

With Senate Democrats up for re-election next year in gun-friendly states ranging from Louisiana to Montana to Alaska, Sen. Patrick J. Leahy, chairman of the Senate Judiciary Committee, said he wasn’t sure that an assault weapons ban could pass the Senate.

Congressional sources said Obama’s proposal to limit the sale of high-capacity magazines faces similar political perils.

Legislation requiring more comprehensive background checks stands a much better chance of passage, Leahy, D-Vt., said at an appearance at Georgetown Law Center. “There are some who say nothing will pass. I disagree with that,” he said. “What I’m interested in is what we can get.”

And even local gun rights activist Harold W. “Budd” Schroeder, of Lancaster, chairman of the Shooters Committee on Political Education, said he could be open to expanding background checks to gun show purchases if there’s evidence that criminals are buying their weapons there.

“People who will be a danger to themselves or others should not have access to guns,” Schroeder said. “None of the legitimate gun owners want those people to have guns. That is the only part of the [Obama] proposal that makes any sense.”

Congressional sources said legislation that would make gun trafficking a felony and would boost federal spending on school safety and mental health also could conceivably pass.

Still, congressional Republicans were, at best, noncommittal about any legislation.

The appropriate House committees will review Obama’s proposals, said Michael Steel, a spokesman for House Speaker John A. Boehner, R-Ohio. “And if the Senate passes a bill,” Steel said, “we will also take a look at that.”

Meanwhile, rank-and-file Republicans were largely hostile to any legislation stemming from Obama’s suggestions.

“I believe he is trampling on the rights of law-abiding citizens” who own guns, said Rep. Chris Collins, R-Clarence. “The president is using this tragedy [in Connecticut] to force through gun legislation and, to some extent, is politicizing tragedy, which I find inappropriate.”

Facing such stiff Republican opposition, Obama also used his executive power to enact 23 initiatives aimed at curbing gun violence.

Most notably, Obama is:

• Requiring federal law enforcement agents to trace guns used in crimes.

• Strengthening penalties for people who lie on gun background checks.

• Bolstering government research on gun violence.

• Setting aside federal grant money for school safety programs and community efforts to keep guns out of the hands of those who should not have them.

• Launching a national gun safety campaign.

Rep. Tom Reed, R-Corning, focused his criticism at the president’s legislative proposals.

“A number of the proposals laid out by the president today place considerable restrictions on Americans’ Second Amendment rights, and I remain concerned that eroding one of our constitutional rights will lead to more limits,” said Reed, who stressed the need for better mental health services instead of gun control.

Gun-control advocates, on the other hand, were thrilled with the president’s proposal. The Brady Campaign to Prevent Gun Violence and New York City Mayor Michael R. Bloomberg both issued statements praising the effort.

And Arlee Daniels, program director of Buffalo’s Stop the Violence Coalition, said: “I think this is long overdue. I hope all of this passes.”

In particular, Daniels said he hopes Congress enacts restrictions on large-capacity magazines.

“There’s no reason to have a 30-round clip unless you’re preparing for war,” he said.

Rep. Brian Higgins, D-Buffalo, also praised Obama for “a very comprehensive proposal,” saying he was pleased that it included not just needed gun regulations, but also an emphasis on mental health issues.

News wire services contributed to this report. email: