The latest social media sparring between a politician and entertainer is getting especially personal, as Rand Paul, the COVID-downplaying Republican senator from Kentucky, took to Twitter to suggest that his having received a suspicious powder at his home might be due to singer Richard Marx “encouraging violence” against him.

“I take these threats immensely seriously,” Paul said in a statement Tuesday. “As a repeated target of violence, it is reprehensible that Twitter allows C-list celebrities to encourage violence against me and my family. Just this weekend Richard Marx called for violence against me and now we receive this powder filled letter.”

Earlier in the day, the FBI was reported to be investigating a large envelope containing an unknown white powder that was delivered to Paul’s home in Kentucky on Monday. The U.S. Capitol Police released a statement saying, “An initial test determined the substance is not dangerous. As a precaution, it was taken to an FBI lab for further testing.”

Marx has become well known in recent years for his caustic tweets against right-wing positions and the politicians who espouse them, often retweeted by followers who’ve come to enjoy his commentary regardless of whether they were fans of his run of pop smashes.

On Sunday, Marx had tweeted, “I’ll say it again: If I ever meet Rand Paul’s neighbor I’m going to hug him and buy him as many drinks as he can consume.” Marx was referring to a 2017 incident in which Paul’s neighbor pled guilty to assaulting a member of Congress after an apparently non-political dispute that left the senator with broken ribs.

Marx has been a frequent critic of Paul’s diminishment of the severity of the COVID-19 crisis and his positions against mask-wearing and mass vaccination.

“You know who actually put multiple people’s lives at potential risk?” Marx tweeted Monday night, linking to a March 2020 news story about how Paul was the first senator to be diagnosed with the coronavirus.

Fox News reported Monday night that the envelope of white powder had been accompanied by a photographic image of Paul in a neck brace, arm cast and on crutches, accompanied by the message, “I’ll finish what your neighbor started, you motherfucker.” The FBI has not confirmed the veracity of Fox’s report.

The singer has mostly been doing retweets since Paul returned fire, although he showed his sense of humor was intact when he responded to a tweeter who wrote “How could you tell if Richard Marx was cancelled?” by saying, “That’s actually very funny” and adding a pair of clapping-hands emoji.

Responding to another dissenter on Twitter Monday, Marx wrote, “It is me who’s bummed that someone who presents as intelligent as you wouldn’t possess the wisdom to both disagree with someone’s politics and like their artistry. I think Jon Voight is a psychotic traitor, but he’s a wonderful actor.”

Marx’s reps did not immediately respond to a request for comment. The singer’s memoir, “Stories To Tell,” comes out July 6.

Marx is not the only entertainer with whom Paul is engaged in a war of words. The senator devoted several tweets Tuesday to addressing TV host Stephen Colbert by his Twitter handle, apparently for something said on the air, since Colbert does not appear to have mentioned Paul on Twitter in recent weeks.