US President Donald Trump has continued to press for the arming of teachers and more school security guards following last week’s mass shooting in Florida.

In front of a cheering crowd of supporters at the Conservative Political Action Conference (CPAC) in Maryland, Trump urged activists to back his Republican Party in the autumn mid-term elections.

Before he left for CPAC event, Trump questioned the alleged inaction of an armed officer who failed to stop the gunman who carried out last week’s massacre at Marjory Stoneman Douglas High School in Parkland, which left 17 people dead.

He told reporters that “when it came time to get in there and do something”, Florida deputy Scot Peterson “didn’t have the courage, or something happened”.

“He certainly did a poor job,” Trump claimed. “But that’s a case where somebody was outside, they’re trained, they didn’t react properly under pressure, or they were a coward.”

Long supported by powerful gun lobby group the National Rifle Association (NRA), Trump has sought to maintain his backing among gun rights activists even as he has called for strengthening background checks and raising the minimum age for purchasing semi-automatic rifles in the wake of the mass killing.

He said that past efforts to address school safety and gun violence had faded and “nothing ever gets done”. He said: “We want to see if we can get it done. Let’s get it done right, we really owe it to our country.”

Trump added: “Most of it’s just common sense. It’s not ‘do you love guns, do you hate guns’. It’s common sense.”

The president predicted that in forthcoming elections this year, Democrats would “take away” massive tax cuts, referencing to his signature tax law signed in December, “and they will take away your Second Amendment”, the right to bear arms.

Trump then surveyed the audience of conservatives on which issue was more important to them, and listened as the crowd cheered loudly in support of the Second Amendment.

Trump’s speech at CPAC came at the end of a week that included meetings with students and teachers and state and local officials on ways to bolster school safety and address gun violence.

Trump said the “evil massacre” at the Florida school had “broken our hearts”. He added that designating schools as “gun-free zones” puts students in “far more danger”.

Trump reiterated his push for “gun-adept teachers and coaches” to be able to carry concealed firearms and said it was “time to make our schools a much harder target for attackers – we don’t want them in our schools”.

If a staff member had been carrying a concealed firearm at the Florida school, “the teacher would have shot the hell out of him before he knew what happened”, Trump insisted.