Democratic presidential candidate Beto O’Rourke early Friday morning characterized an incendiary tweet from a Texas state representative as “a death threat” against him, and charged that the Republican lawmaker should be stripped of his assault weapon.

O’Rourke, a former Texas congressman, championed hardline gun reforms at Thursday night’s Democratic primary debate in Houston, calling for a mandatory federal buyback of military-style firearms following a mass shooting last month in his hometown of El Paso that killed 22 people.

“Hell yes, we’re going to take your AR-15, your AK-47,” O’Rourke declared to energetic applause from the forum’s audience at Texas Southern University. “We’re not going to allow it to be used against our fellow Americans any more.”

After O’Rourke’s campaign repeated an abbreviated version of that line from the candidate in a tweet, Briscoe Cain — who represents the state’s House District 128, east of Houston — wrote online: “My AR is ready for you Robert Francis.”

O’Rourke responded just after midnight to Cain’s post, which was taken down by Twitter. “This is a death threat, Representative. Clearly, you shouldn't own an AR-15—and neither should anyone else,” he wrote.

Cain offered a retort less than 20 minutes later, again employing O'Rourke's legal name and tweeting: “You’re a child Robert Francis.”

O'Rourke said in an interview later Friday morning that his campaign staff had contacted the FBI and Twitter regarding Cain's tweet.

"I mean, anytime you have somebody threatening to use violence against somebody in this country to resolve a political issue, or really for any reason, that's a matter for law enforcement," O'Rourke told CNN.

"But it really drives home the point better than I could have made," he continued. "Rep. Briscoe Cain is making the case that no one should have an AR-15 that they can hold over someone else in this country — say, 'Look, if we disagree on something, let me introduce you to my AR-15.' Absolutely wrong."

National Democrats and some Republicans have pushed for various gun reform policies following a spate of mass shootings over the summer in California, Texas and Ohio.

All of the Democratic candidates vying to challenge President Donald Trump in 2020 support instituting a system of universal background checks and an assault weapons ban — with some promoting a mandatory buyback of the firearms and others in favor of a voluntary program.