Those blaming the deadly Parkland shooting on the National Rifle Association need to take a harder look at the Broward County school superintendent and sheriff, according to NRA spokesperson Dana Loesch.

She told the Western Conservative Summit that school authorities “protected” the confessed mass shooter by failing to get tough on him in the name of reducing student arrests prior to the Feb. 14 shooting.

“He was sending death threats to other classmates through social media platforms which under Florida law, under the state statute, that’s a felony,” said Ms. Loesch. “But because of that Promise program which he was enrolled in, none of it was reported. It was all under the radar. He didn’t have a criminal record because [superintendent] Robert Runcie and [Sheriff] Scott Israel prevented him from having one.”

She added, “They might as well have walked into the gun store and bought the gun for him.”

Ms. Loesch capped the annual conservative gathering Saturday night by pushing back against the movement to hold the NRA responsible for the Parkland shooting, pointing to the district’s lax discipline policies and security measures.

Her comments came shortly after anti-NRA demonstrators held a protest outside the Colorado Convention Center.

“I’m sick of seeing my fellow students get killed in their schools for just trying to get an education,” student activist Emmy Adams told CBS4 in Denver.

At the other end of the student spectrum was Kyle Kashuv, a 17-year-old survivor of the shooting at Marjory Stoneman Douglas High School in Parkland, Florida, who drew cheers from the summit crowd as he accused progressives of taking advantage of the tragedy to advance a political agenda.

“Here’s what happened at my school: Immediately after, the left mobilized and used this beneficial opportunity to push for gun control,” Mr. Kashuv said. “They didn’t waste a single second at all. The left, mainstream media and celebrities came out from everywhere and every single corner to push for gun control.”

Mr. Kashuv, now with the conservative student group Turning Point USA, called for an end to gun-free zones in schools, which puts him at odds with David Hogg and Emma Gonzalez, Parkland students who have become nationally recognized gun-control advocates.

The Broward County school district has acknowledged that 19-year-old Nikolas Cruz was briefly enrolled in Promise, a program aimed at keeping low-level offenders out of the “school-to-prison pipeline” by providing counseling instead of suspending, expelling or arresting them.

“They protected his criminal activity,” said Ms. Loesch.

Although the police were repeatedly called to his home, he was never arrested, nor was he detained for mental-health treatment under Florida’s Baker Act.

“To recap, 45 calls, a superintendent and a sheriff who knowingly prevented a criminal record from being established that allowed this very dangerous mentally unstable individual to legally purchase a firearm,” said Ms. Loesch. “They could have Baker Acted him, they could have followed up on the felony charge, he would have been immediately a prohibited possessor.”

Instead, she said, “They did nothing, he murdered 17 people, and it’s all the fault of the NRA and Dana Loesch.”

The NRA has come been the target of protests and boycotts since the Valentine’s Day massacre, which left 17 dead, and the May 18 school shooting in Santa Fe, Texas, which saw 10 killed.

Mr. Runcie has defended the Promise program, which was unveiled in 2013 amid a national push to keep disruptive kids in school and reduce minority suspension, expulsion and arrest rates.

Under the Obama administration, the Department of Education Office for Civil Rights released a 2014 Dear Colleague guidance that threatened school districts with civil-rights investigations unless they reduce racial disparities in discipline.

Hundreds of schools have since enacted policies designed to reduce expulsions and arrests, but Education Secretary Betsy DeVos is reviewing whether to rescind the directive amid complaints from teachers and parents about school chaos.

Ms. Loesch urged parents to find out whether their school districts have begun programs like Promise, which she called “dangerous.”

“It’s protecting criminals and it contributed to this,” said Ms. Loesch.