Cain - a Republican representing east Harris County that includes parts of Deer Park, La Porte and Baytown - tweeted, "My AR is ready for you Robert Francis," in response to presidential candidate Beto O'Rourke, who strongly vowed to ban those types of weapons.
RELATED: Raw interview with Republican Texas state representative, Briscoe Cain
On stage at the Texas Southern University debate, the former El Paso Congressman said in response to a question on gun control, "Hell yes, we're gonna take your AR-15!"
SEE MORE: Texas lawmaker to Beto O'Rourke: 'My AR is ready for you'
That same exclamation was tweeted from his official Twitter account, which Cain responded to.
After Cain's response, O'Rourke called out the GOP lawmaker.
"This is a death threat, Representative. Clearly, you shouldn't own an AR-15--and neither should anyone else," O'Rourke tweeted.
Cain replied, "You're a child Robert Francis."
On Friday, Cain told ABC13 Eyewitness News the tweet was not a threat, but rather a paraphrase of a well-known Texas motto.
"It's long been the unofficial motto of the state of Texas: 'Come and Take It' at the Battle of Gonzalez, which occurred October 2, 1835," Cain said. "The anniversary is coming up. And that's really what that means, is 'Come And Take It.'"
O'Rourke's campaign confirmed to ABC13 it has contacted the FBI. Cain said he has not heard from federal authorities, but his Twitter account was temporarily suspended because he refused to pull the tweet and others reported it to Twitter.
The O'Rourke camp is now selling T-shirts with the phrase.
"I'm not too surprised that he would take something and use it for political gain," Cain observed.
Asked if he thinks the government could ban or buy back assault-style rifles or high capacity semi-automatic weapons like AR-15s, Cain said, "Over my dead body. It's not going to happen. It's a bad idea to take things from the American people."
Cain added his wife is currently under the protection of the Department of Public Safety because of threats his family received. Cain, though, said he loves Twitter and won't remove his account.
The state lawmaker, who was first elected in 2016, does indeed own an AR-15. According to Cain, he keeps it mounted to the wall of his Texas Capitol office during the legislative session and takes it down to lock it up when he's not in Austin.
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