President Donald Trump speaks during the Public Safety Medal of Valor awards ceremony in the East Room of the White House, Feb. 20, 2018, in Washington.
President Donald Trump speaks during the Public Safety Medal of Valor awards ceremony in the East Room of the White House, Feb. 20, 2018, in Washington.

U.S. President Donald Trump said Monday he is waiting for the outcome of court cases before deciding whether to take action on raising the age to buy guns, but conceded there is little political support to do so.

Hours after White House officials laid out gun-law changes they want enacted in the wake of last month's deadly shooting at a Florida high school that left 17 dead, Trump said on Twitter that "very strong improvement and strengthening of background checks [for gun purcahsers] will be fully backed." He said that bump stocks, which boost the firepower of some assault weapons, "will soon be out."

WATCH: Trump gun safety

?In addition, he said, "highly trained expert teachers will be allowed to conceal carry [weapons in schools], subject to State Law. Armed guards OK, deterrent!"

But he added that he has held off on increasing the minimum age for gun purchases from 18 to 21, "while watching court cases and rulings before acting." He said states, absent changes adopted by Congress, are acting on their own to increase the gun-buying age.

Florida enacted its own law last week banning the purchase of firearms by anyone under the age of 21.

The National Rifle Association lobbying group has filed a lawsuit challenging the law, calling it "an affront" to the U.S. Constitution's Second Amendment, which many believe enshrines gun ownership.

WATCH: Student walkout

Trump had earlier endorsed increasing the age restriction, but the White House only pledged Sunday to help individual states provide "rigorous firearms training" to some teachers and endorsed a bill to tighten the federal background check system for gun purchasers.

"We are focusing on things we can do immediately," White House press secretary Sarah Huckabee Sanders told reporters on Monday.

Trump said on Twitter that if schools in the U.S. are mandated to be "gun free zones" then "violence and danger are given an open invitation to enter."

In a conference call with reporters, administration officials said Trump will urge states to give law enforcement the power to temporarily seize guns from people or prevent them from purchasing the weapons if they demonstrate a threat. The president will also support expanding mental health programs.

There has been an increased national U.S. focus on gun control policy following the mass shooting at the Florida high school. Authorities have charged a 19-year-old man who a year was expelled from the school with the killings, saying he used a semi-automatic rifle.

Many students from Marjory Stoneman Douglas High School in Parkland, Fla., have been vocal in calling for state and national leaders to take actions to ensure another such shootings do not happen again. Students across the country are planning a walkout Wednesday, the one-month anniversary of the Parkland shooting, as well as a march in Washington on March 24.

Local residents show their support as students arr
Local residents show their support as students arrive at Marjory Stoneman Douglas High School for the first time since the mass shooting in Parkland, Florida, Feb. 28, 2018.

Trump wants to help states train specially qualified school personnel who volunteer to carry firearms and to encourage military veterans and retired police officers to seek new careers as teachers.

The idea of arming some teachers has been controversial and has drawn sharp opposition from the National Education Association, the country's largest teachers lobby, among other groups. NEA President Lily Eskelsen Garcia has said teachers should be focused on educating students and that there need to be solutions that will "keep guns out of the hands of those who want to use them to massacre innocent children and educators."

Under the White House plan, Education Secretary Betsy DeVos will chair a commission on school safety and violence that will report recommendations to Trump, probably within a year, according to administration officials. The panel will focus on a number of areas, including existing rating systems for "violent entertainment," effects of press coverage of mass shootings, campus security best practices and the effectiveness of "psychotropic medication for treatment of troubled youth."

Secretary of Education Betsy DeVos, left, speaks w
Secretary of Education Betsy DeVos, left, speaks with Commissioner Pam Stewart of the Florida Department of Education before a meeting between President Donald Trump and state and local officials to discuss school safety, in the Roosevelt Room of the White House, Feb. 22, 2018, in Washington.

DeVos characterized the administration's efforts as "a pragmatic plan to dramatically increase school safety."

"We are committed to working quickly because there's no time to waste," DeVos told reporters. "No student, no family, no teacher and no school should have to live the horror of Parkland or Sandy Hook or Columbine again."

Senate Minority Leader Charles Schumer criticized the White House plan in a tweet Sunday night, saying the administration "has taken tiny baby steps designed not to upset" the NRA while a gun violence epidemic "demands giant steps be taken." He pledged Democrats will push for stricter steps, including universal background checks for gun buyers and a ban on assault weapons.