It's no secret that top presidential adviser Kellyanne Conway and her husband, a frequent Trump critic, don't see eye to eye on the president. On Monday, they duked it out on Twitter after conservative lawyer George Conway needled his wife about a Joe Biden tweet.

Kellyanne Conway had retweeted a brief video clip of the former vice president speaking to a crowd, along with a comment: “Sleepy Joe is Creepy Joe,” she wrote. “We need Ukraine’s help to defeat THIS guy?”

To which George Conway responded: “Your boss apparently thought so.”

Such online sparring has become a staple of the Trump presidency. Earlier this year, after George Conway suggested that Trump wasn’t mentally fit to serve, the president called him “a total loser,” “the husband from hell” and a “whack job.”

“You. Are. Nuts,” the lawyer responded on Twitter.

But speaking to Politico, Kellyanne Conway defended the president, saying he should be able to respond after a “non-medical professional accused him of having a mental disorder.”

A few months before that, one of the president’s sons, Eric Trump, said George Conway’s White House views were among the ugliest in modern politics.

“The utter disrespect George Conway shows toward his wife, her career, place of work, and everything she has fought SO hard to achieve, might top them all,” he wrote.

Marriage historian Stephanie Coontz has said there are few historical precedents that compare to the Conways’ increasingly high-profile clashes.

“Perhaps the couple is playing a competitive political game, with neither caring enough about the real-world impact of the actions they so strenuously defend or condemn to erode their love for each other,” she wrote. “But that’s still a dangerous script for a marriage.”