As a grieving Florida community demanded action on guns, President Donald Trump on Tuesday directed the Justice Department to move to ban devices like the rapid-fire bump stocks used in last year's Las Vegas massacre. It was a small sign of movement on the gun violence issue that has long tied Washington in knots.

"We must do more to protect our children," Trump said, adding that his administration was working hard to respond to the shooting in Parkland that left 17 dead.

After past mass killings yielded little action on tighter gun controls, the White House is trying to demonstrate that it is taking the issue seriously. The president, a strong and vocal supporter of gun rights, has not endorsed more robust changes sought by gun control activists. But the White House cast the president in recent days as having been swayed by the school shooting in Florida and willing to listen to proposals.

In a tweet Tuesday night, Trump indicated he wants to strengthen the background check system, but offered no specifics.

"Whether we are Republican or Democrat, we must now focus on strengthening Background Checks!"

Asked at a press briefing Tuesday if Trump was open to reinstating a ban on assault-type weapons, spokeswoman Sarah Huckabee Sanders said White House officials "haven't closed the door on any front." She also said that the idea of raising the age limit to buy an AR-15 was "on the table for us to discuss."

Still, Sen. Chris Murphy, a Connecticut Democrat and leading advocate for tighter gun controls, said Trump's directive suggested the president was aware of fresh energy on the issue and called it a sign that "for the first time" politicians are "scared of the political consequences of inaction on guns." The president's action was "a small, but vital step in the history of our movement" against gun violence, Murphy added.

Trump said he wanted to crack down on a device that was used in the October shooting in Las Vegas that left 58 people dead. A bipartisan legislative effort to ban bump stocks last year fizzled out.

The Bureau of Alcohol, Tobacco, Firearms and Explosives announced in December that it was reviewing whether weapons using bump stocks should be considered illegal machine guns under federal law. Trump on Tuesday signed a memorandum directing the agency to complete the review as soon as possible and propose a rule "banning all devices that turn legal weapons into machine guns."

The Department of Justice, reacting to Trump's memo, said in a statement that it "understands this is a priority for the president and has acted quickly to move through the rulemaking process. We look forward to the results of that process as soon as it is duly completed."

A day earlier, Trump sent another signal he had been swayed by the Parkland shooting and the dramatic calls for action in its aftermath. A White House statement said Trump was looking at a bill that would strengthen federal gun background checks. On Wednesday, he will host parents, teachers and students at the White House for a "listening session" that will include people impacted by mass shootings in Parkland, Columbine, Colorado and Newtown, Connecticut.

The president was moved by a visit Friday with Florida victims in the hospital and is trying to work on solutions, said a person familiar with his thinking who sought anonymity to discuss internal conversations. Background checks and tackling mental health are two areas of interest for the president.

Among the steps sought by gun control advocates: closing loopholes that permit loose private sales on the internet and at gun shows, banning assault-type weapons and to passing laws to enable family members, guardians or police to ask judges to strip gun rights temporarily from people who show warning signs of violence.

The federal background check bill was developed in response to a mass shooting last November in which a gunman slaughtered more than two dozen people at a Texas church. It would penalize federal agencies that don't properly report required records and reward states that comply by providing them with federal grant preferences. The measure, which is pending in the Senate, was drafted after the Air Force acknowledged that it failed to report the Texas gunman's domestic violence conviction to the National Criminal Information Center database.

The GOP-controlled House paired the background checks bill with a measure making it easier for gun owners to legally carry concealed weapons across state lines. The concealed carry measure, a top priority of the National Rifle Association, would allow gun owners with a state-issued concealed-carry permit to carry a handgun in any state that allows concealed weapons.

Murphy said any attempt to combine background checks with concealed-carry provisions would significantly jeopardize the chances of passing bipartisan reform of the background checks system. He called a national concealed weapons law "a terrible, dangerous idea" that would allow a criminal who bought a gun without a background check in Florida to carry that same gun, concealed under his clothing, into New York's Times Square or other crowded areas.

Meanwhile at the Florida Statehouse, a Democratic representative asked for a procedural move that would have allowed the Republican-controlled House to consider a ban on large-capacity magazines and assault-style rifles such as the AR-15 that was wielded by the suspect, Nikolas Cruz.

The bill had been assigned to three committees but was not scheduled for a hearing. The House quickly nixed the Democratic motion. The vote broke down along party lines, and Republicans criticized Democrats for forcing the vote.

Because the committees will not meet again before the legislative session ends March 9, the move essentially extinguishes hope that lawmakers would vote on any sweeping measures to restrict assault rifles, although other proposals could still be considered.

"No one in the world with the slightest little hint of a soul isn't moved by this tragedy," Republican strategist Rick Wilson said. "The discussion has to be a longer, bigger and broader discussion."

Lizzie Eaton, a junior at Marjory Stoneman Douglas High School, spent the day lobbying senators of both parties and concluded that lawmakers were "just not listening to us."

The vote was "heartbreaking," she said. "But we're not going to stop."

The students planned to hold a rally Wednesday to put more pressure on the Legislature.

"I really think they are going to hear us out," said Chris Grady, a high school senior aboard the bus.

The Feb. 14 attack initially appeared to overcome the resistance of some in the state's political leadership, which has rebuffed gun restrictions since Republicans took control of both the governor's office and the legislature in 1999. However, many members of the party still have strong resistance to any gun-control measures.

Republican leaders in the House and Senate say they will consider raising age restrictions for gun purchases and temporarily revoking someone's guns if that person is deemed a threat to others. Gov. Rick Scott, also a Republican, convened groups assigned to propose measures for protecting schools from gun violence.

Lawmakers will probably say that getting a new bill passed is nearly impossible with only two-and-a-half weeks left in the legislative session. Some lawmakers who are thinking of running on a statewide ticket are mindful of their sensitive positions, since gun owners make up huge voting blocs in some parts of the state, especially the Panhandle.

Wilson said he knows the students "want something to happen," and they need "a moment to come and make their case."

But, he said, "the thought that you get to wave a wand and change the law is something that is probably going to collide with reality."

The Parkland students also plan to meet Wednesday with top legislative leaders, including House Speaker Richard Corcoran and Senate President Joe Negron.

Florida has a reputation for expanding gun rights. Negron sponsored a 2011 bill that Scott signed into law that banned cities and counties from regulating gun and ammunition sales.

Authorities said Cruz, 19, had a string of run-ins with school authorities that ended with his expulsion. Police were repeatedly called to his house throughout his childhood. His lawyers said there were many warning signs that he was mentally unstable and potentially violent. Yet he legally purchased a semi-automatic rifle.

The State Senate is also considering boosting spending on mental health programs for schools and giving law-enforcement greater power to involuntarily hold someone considered a danger to themselves. The chamber will also look at a proposal to deputize a teacher or someone else at school so they are authorized to have a gun.

Kyle Kashuv, a 16-year-old student at the high school, said he was pro-gun prior to the shooting.

"I had no issue with anyone having a gun of any caliber," said Kashuv, as he rode in the bus to Tallahassee. "I was all for it. But after the situation, I realized we have some issues in our society and it has to be addressed.

The fact that someone who was so steadfast in support of gun rights now acknowledges the need for changes "really shows how important what we're doing is," he said.