President Donald Trump on Monday flipped out at longtime Republican strategist and Fox News personality Karl Rove, calling him a “stone cold loser.”

“Karl Rove is so bad for the Republican Party, and completely wrong so often,” Trump wrote on Truth Social. “He suffers from a major case of Trump Derangement Syndrome primarily because, for almost 10 years, I beat back and won against so many of the people and things that he wanted and espoused.”

Trump also wondered why Fox News and The Wall Street Journal ― where Rove writes a weekly column ― “keep his RINO voice alive.”

Donald Trump on Truth Social

Donald Trump

It’s not clear what prompted Trump’s attack, but it appeared shortly after reports surfaced that Rove was planning to vote for a Democratic candidate for the first time in more than 30 years. Rove, a key architect of George W. Bush’s 2000 and 2004 presidential victories, reportedly described Bo French ― a Republican candidate for statewide office in Texas ― as a “bigot” for a racist social media post he made over the weekend.

The Texas Tribune reported that Rove told a private lunch event that he would be voting for French’s rival, Democratic candidate Jon Rosenthal, for the Texas Railroad Commission. Rove noted that he’d only voted for one other Democrat: then-Lt. Gov. Bob Bullock in 1994.

Rove has been critical of Trump at times, saying he was “nervous” about the impact of last week’s midterm convention, and warning that the president’s “narcissism” could cost the party in the November elections.