WASHINGTON -- U.S. President Donald Trump told conservatives that even Second Amendment supporters can get behind steps to fight gun violence, offering a red-meat call for arming teachers Friday while avoiding mention of other elements of his approach opposed by the National Rifle Association.

Basking in the glow of a cheering crowd, Trump also offered a greatest-hits recap of his campaign themes during wide-ranging remarks to the Conservative Political Action Conference. He urged activists to help Republicans in the fall midterm elections and heed his recent calls to address gun violence.

Trump questioned the inaction of an armed officer who failed to stop the gunman who carried out last week's Florida massacre. Departing the White House for CPAC, Trump 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."

Long supported by the National Rifle Association, the president 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.

Trump said that past efforts to address school safety and gun violence had faded and "nothing ever gets done. We want to see if we can get it done. Let's get it done right, we really owe it to our country." He added, "most of it's just common sense. It's not 'do you love guns, do you hate guns.' It's common sense."

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. He said the "evil massacre" of 17 people at the Florida high school had "broken our hearts."

Trump declined to reiterate his proposal to increase age restrictions for the purchase of firearms, an idea the NRA has opposed. But at separate event with the nation's governors, who are attending a weekend conference, Vice-President Mike Pence noted that Trump had called for raising the age to 21, part of what Pence called "working with leaders in the Congress to bring this evil in our time to an end."

The White House has said Trump will soon lay out a package of school and gun safety proposals for Congress to consider. Connecticut Chris Murphy, an outspoken advocate for more gun restrictions after the 2012 elementary school shooting in Newtown, Connecticut, said he expected to meet with White House aides next week.

"I'm here to hear the White House out," Murphy said.

Trump said designating schools as "gun-free zones" puts students in "far more danger." He 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 teacher 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 said.

Officials announced Thursday that Peterson never went inside to engage the gunman at Marjory Stoneman Douglas High School while the shooting was underway. Peterson has resigned.

Turning to this year's elections, Trump told conservative activists at CPAC that Republicans must not be complacent in the fall midterms, warning of terrible consequences if Democrats take control of Congress.

Trump predicted Democrats would "take away those massive tax cuts," referencing to his signature tax law signed in December, "and they will take away your Second Amendment." 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 right to bear arms.

Near the end of a roughly 75-minute speech, Trump recited the lyrics from the 1960s song, "The Snake," a campaign staple that served as an allegory to warn of what he views as the dangers of some refugees and immigrants being allowed into the United States. Trump reiterated his campaign pledge to build a wall along the U.S.-Mexican border and charged Democrats with failing to engage on a plan to provide protections for young immigrants, even though he ended the program.

Trump argued that his administration has kept his campaign promises, boasting as he often does that he "had the most successful first year in the history of the presidency."

And he re-aired rhetoric from his 2016 campaign, citing a "very crooked media, we had a crooked candidate, too, by the way," referencing former Democratic rival Hillary Clinton. The crowd chanted, "lock her up," a common refrain at Trump campaign rallies.

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Associated Press writer Darlene Superville contributed to this report.