ST. LOUIS – Democratic Sen. Claire McCaskill and an independent candidate running for her job support banning assault weapons to stifle the sort of violence that killed 17 at a Florida high school, while the likely Republican challenger says efforts should focus on keeping guns out of the hands of criminals and the mentally ill.

The Missouri race is among the most closely watched this year, with control of the Senate potentially at stake. The issue of gun violence emerged as a key topic after a 19-year-old with an assault rifle killed 14 students and three teachers last week in Parkland, Florida.

McCaskill supports an assault weapons ban, a campaign spokeswoman said Thursday, and voted for a ban in 2013. Meanwhile, independent candidate Craig O'Dear called for a "responsible ban on assault rifles and large capacity magazines," while acknowledging he owns such a gun.

"As a gun owner and strong supporter of Second Amendment rights, I have concluded that the presence of assault rifles in American civilian life is not a Second Amendment issue," O'Dear, a Kansas City attorney who announced his candidacy last week, said in a news release. He also favors measures such as better background checks and modification of mental health privacy laws.

Republican candidate Josh Hawley said it should be an "urgent priority" to keep all types of guns away from the mentally ill "while protecting citizens' constitutional right to keep and bear arms."

McCaskill and O'Dear face some political risk. Missouri has moved decidedly conservative in recent years, backing Republican Donald Trump by nearly 20 percentage points in 2016.

McCaskill, in a statement to The Associated Press, said she supports "common sense gun safety measures to keep our children safe, including strengthening background checks, banning bump stocks, closing the gun show loophole, and ensuring that anyone who is too dangerous to get on an airplane can't get their hands on a gun."

Bump stocks are a device that allows a semi-automatic rifle to mimic the rapid fire of a machine gun. A bump stock was used by the gunman who killed 58 people in Las Vegas in October.

"I'm hopeful that this time my colleagues listen to the incredible students from Parkland who are speaking out to say that it's far past time for Congress to take action," McCaskill said.

Hawley, Missouri's attorney general, said in a statement to AP that he also favors a ban on bump stocks. He supports strengthening background checks and blamed McCaskill and others in Congress for failing to require additional mental health records in the National Criminal Instant Background Check System.

"Right now, there are too many mental health records falling through the cracks," Hawley said. "Congress had the chance to solve this problem and failed. We must act now."

Hawley said enhanced school security options should be considered, such as programs "to train and arm security personnel," video monitoring of entrances and metal detectors.