President Trump on Feb. 20 said he signed a memorandum ordering the attorney general to change regulations to ban ¡°bump stocks.¡± (Reuters)

President Trump on Tuesday signaled an openness to modest gun-control measures following what he called an ¡°evil massacre¡± at a South Florida high school last week that left 17 dead and prompted passionate calls from teenagers for reform.

Trump directed the Justice Department to draft a ban on devices known as ¡°bump stocks,¡± molded pieces of plastic or metal that can attach to a legal semiautomatic gun and allow it to fire up to 100 rounds in seven seconds, similar to an illegal machine gun.

In private, he has indicated that he might do more, telling advisers and friends in recent days that he is determined to push for some sort of gun-control legislation, according to people familiar with the conversations.

In one such discussion, during dinner with television commentator Geraldo Rivera at Trump¡¯s Mar-a-Lago Club in Palm Beach, the president listened with interest as Rivera suggested raising the minimum age at which a person could buy a semiautomatic weapon from 18 to 21. White House press secretary Sarah Huckabee Sanders told reporters Tuesday that the idea is ¡°on the table for us to discuss.¡±

So far, Trump¡¯s public stances have not crossed the agenda of the powerful pro-gun-rights National Rifle Association, which endorsed him during the 2016 Republican primary and spent more than $30 million supporting his candidacy and attacking his opponent in the general election, Hillary Clinton. But behind the scenes, Trump is floating ideas that could put him at odds with the NRA.

As active shooter incidents become more common and more deadly, here's how President Trump has responded to four that unfolded under his presidency. (Jenny Starrs/The Washington Post)

The NRA did not respond Tuesday to a request for comment and has not publicly weighed in on the potential gun control measures being floated from Tallahassee to Washington, but that may change Wednesday night. NRA spokeswoman Dana Loesch is expected to participate in a CNN town hall in South Florida along with elected officials and classmates and parents of Douglas victims.

Trump¡¯s attempt at a new tone on the gun issue comes as the politics surrounding the issue appear to be changing in the wake of the shooting last week in Parkland, Fla.

Students who survived the shooting are calling for increased gun control, and some have pledged not to return to class until changes are made. On Tuesday, about 100 students from the school traveled to Tallahassee to press state lawmakers on the need for gun-control legislation. But as their buses were on the road, the Republican-controlled House voted against any debate on banning weapons like the one used in the attack.

Meanwhile, a new Washington Post-ABC News survey released this week found that more than 6 in 10 Americans fault Congress and Trump for not doing enough to prevent mass shootings.

Trump plans to meet Wednesday with students, teachers and parents who were affected by mass shootings, including the one in Parkland. The group will also include people from the Washington area who have not experienced a mass shooting.

¡°We¡¯re working very hard to make sense of these events,¡± Trump said at the White House on Tuesday afternoon. ¡°I met with some of the survivors and their families, and I was moved ¡ª greatly moved, greatly moved ¡ª by their strength, their resilience. .?.?. We must do more to protect our children. We have to do more to protect our children.¡±

Bipartisan action has been elusive following previous mass shootings, including some of the deadliest rampages in modern U.S. history. After the 2012 shooting at Sandy Hook Elementary School in Connecticut ¡ª in which 20 children and six adults were gunned down ¡ª an effort to expand background checks and ban certain rifles failed in Congress. The NRA refused to endorse the bill, scuttling its chances in the Senate by putting pressure on Republicans and a handful of moderate Democrats who faced reelection that year and ultimately voted against the legislation.

Sen. Patrick J. Toomey (R-Pa.), who spearheaded that unsuccessful bipartisan agreement, said Tuesday that he plans to introduce legislation in the coming weeks that would expand background checks on firearm purchases.

¡°It does feel like we have a shot at getting a little bit of momentum on background checks,¡± Toomey said in an interview.

The White House said Monday that Trump supports efforts to ¡°improve the federal background check system.¡±

¡°Bump stocks¡± were not used in last week¡¯s shooting in Florida, according to a law enforcement official.

But they gained notice after 58 people were killed and hundreds wounded in October at a country music festival in Las Vegas, where authorities said the shooter had 14 AR-15s with bump stocks and other firearms.

The NRA said that it would support more regulation of bump stocks, but it opposed legislative action. Republican lawmakers punted the issue to the Bureau of Alcohol, Tobacco, Firearms and Explosives, which said it cannot regulate bump stocks unless Congress changes the law.

In December, the Justice Department seemed to signal a change in attitude and began exploring the possibility of outlawing bump stocks by changing federal regulations, a lengthy process that involves posting a public notice and soliciting comments from those with an interest. The period for accepting public comments closed Jan. 25, though officials are still weighing what to do. Trump said the department received 100,000 comments.

On Tuesday afternoon, Trump signed a memorandum that directed the Justice Department ¡°to dedicate all available resources to complete the review of the comments received, and, as expeditiously as possible, to propose for notice and comment a rule banning all devices that turn legal weapons into machine guns.¡±

If the rule is changed, it could meet legal challenges ¡ª especially from bump-stock manufacturers that have continued to sell the devices while federal authorities contemplate regulating them. A Justice Department official said the White House and the Justice Department had been in touch before the president issued his memo on Tuesday. The official said the White House Counsel¡¯s Office also carefully vetted the president¡¯s memo to try to make sure it would not have any negative effects on possible future litigation.

Given that a regulation change would probably be challenged, Sen. Dianne Feinstein (Calif.), the ranking Democrat on the Senate Judiciary Committee, said Tuesday that Trump needs to instead support legislation to ban bump stocks. A prolonged court fight, she said, could mean that ¡°bump stocks would continue to be sold¡± for years. ¡°Legislation is the only answer.¡±

Much of the public debate since last week¡¯s shooting at Marjory Stoneman Douglas High School has focused on warning signs raised before the massacre and how the 19-year-old suspect was able to legally purchase at least 10 rifles and shotguns.

Sanders said Tuesday that increasing the minimum age for purchasing a semiautomatic weapon is ¡°certainly something that¡¯s on the table for us to discuss and that we expect to come up over the next couple of weeks.¡±

Another idea being floated by members of the Trump administration and close allies: increasing the number of armed teachers and stationing retired law-enforcement officers at schools.

The Parkland shooting was Florida¡¯s third mass shooting in as many years, and all three have occurred despite armed officers being on the premises.

At the high school in Parkland, authorities say an armed school resource officer was on the school¡¯s 45-acre campus, but he never encountered the gunman during the five-minute rampage.

Scott Clement, Ed O¡¯Keefe, Robert Costa, Matt Zapotosky and Aaron Davis contributed to this report.