Parents, teachers and students affected by school shootings over the past two decades have met President Donald Trump as the White House sought to show resolve against gun violence.

A strong supporter of gun rights, Mr Trump has indicated in recent days that he is willing to consider ideas not in keeping with National Rifle Association orthodoxy, including age restrictions for buying assault-type weapons.

The president is facing growing calls for action on gun control after the mass shooting that left 17 dead at Marjory Stoneman Douglas High School in south Florida.

School Shooting Florida
Students are demanding action on gun control (Gerald Herbert/AP)

Mr Trump has said he wants to listen and has offered support for some limited gun-control measures but gun owners are a key part of his base.

Television personality Geraldo Rivera had dinner with Mr Trump at his private Palm Beach club over the weekend and described Mr Trump as “deeply affected” by his meeting on Friday with survivors of the Flordia shooting .

Mr Rivera said he and Mr Trump discussed the idea of raising the minimum age to purchase assault-type weapons.

Mr Trump “suggested strongly that he was going to act to strengthen background checks”, Mr Rivera said.

Mr Trump embraced gun rights on his campaign, though he supported some gun control before he became a candidate, backing an assault weapons ban and a longer waiting period to purchase a gun in a 2000 book.

Throughout the day on Wednesday, television news showed footage of student survivors of the violence marching on the Florida state Capitol, calling for tougher laws.

The protests came closer to Mr Trump too, with hundreds of students from suburban Maryland attending a rally at the Capitol and then marching to the White House.

Daniel Gelillo, a senior at Richard Montgomery High who helped organise the protest, said students were hoping to pressure lawmakers to act. He said that “up ’til now nothing has quite fazed them”.

On Tuesday, Mr Trump directed the Justice Department to move to ban devices like the rapid-fire bump stocks used in last year’s Las Vegas massacre. The White House has also said Mr Trump was looking at a bill that would strengthen federal gun background checks.

School Shooting Florida
People participate in a gun control rally (Gerald Herbert/AP)

But those moves have drawn criticism as being inadequate, with Democrats questioning whether the Justice Department even has authority to regulate bump stocks and arguing that the background check legislation would not go far enough.

Senator Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, said the federal Bureau of Alcohol, Tobacco, Firearms and Explosives lacks authority under current law to ban bump stocks.

“If ATF tries to ban these devices after admitting repeatedly that it lacks the authority to do so, that process could be tied up in court for years, and that would mean bump stocks would continue to be sold,” said Ms Feinstein, of California, calling legislation the only answer.