President Trump on Monday seized on a joke from Senate Intelligence Committee ranking Democrat Mark Warner over the weekend that the Virginia senator has inside information on special counsel Robert Mueller’s investigation. 

Why is Senator Mark Warner (D-VA), perhaps in a near drunken state, claiming he has information that only he and Bob Mueller, the leader of the 13 Angry Democrats on a Witch Hunt, knows? Isn’t this highly illegal. Is it being investigated?

— Donald J. Trump (@realDonaldTrump) June 25, 2018

The tweet was sent as Trump was onboard Air Force One en route to a rally in Columbia, S.C.{mosads}

The president was referencing a joke Warner made during a dinner Friday night in Martha’s Vineyard as part of a Democratic Senatorial Campaign Committee retreat.

Rachel Cohen, a spokeswoman for Warner, responded that the senator’s comment was “obviously a joke.”

Because it was obviously a JOKE. (Admittedly, not a very GOOD joke.) Why is our President spending time on this today? https://t.co/VafTmu7IyX

— rcohen (@rcohen) June 25, 2018

Politico reported that Warner told the more than 100 guests in attendance to “buckle up” for a “wild couple of months” in the special counsel’s probe into Russian interference in the 2016 election. 

“If you get me one more glass of wine, I’ll tell you stuff only Bob Mueller and I know,” Warner joked.

Warner is the top Democrat on the Senate Intelligence panel, which is conducting an investigation of its own into Russian interference.

While Trump has not often attacked Warner, he has frequently railed against Mueller’s probe, calling it a “witch hunt” and a “hoax.”

Four former Trump associates have pleaded guilty or been indicted in Mueller’s probe thus far. The special counsel also filed charges against 13 Russians and three Russian entities for alleged meddling in the 2016 election.