At a Harris campaign event Thursday evening, former Rep. Liz Cheney urged voters to “reject the depraved cruelty of Donald Trump.” Hours later, Trump lashed out at his fellow Republican on Truth Social, posting a long screed against her and her father, former Vice President Dick Cheney, who has also endorsed Harris.

Trump criticized the former Wyoming representative for her role in the Jan. 6 House select congressional committee and trashed her father for “our ridiculous journey into the Middle East, where Trillions of Dollars were spent, millions of people were killed.”

“What a pathetic couple that is, both suffering gravely from Trump Derangement Syndrome,” he wrote in his post.

Trump’s long-held animosity toward Cheney stems from her vocal criticism of his role in the Jan. 6 riot and her vote to impeach him afterward. Her fierce opposition to Trump arguably contributed to her primary race loss in 2022 by a huge margin.

Yet, Cheney has remained one of Trump’s most relentless Republican critics, and her remarks at the event at Ripon, Wisconsin, clearly struck a nerve with him.

“I was a Republican even before Donald Trump started spray-tanning,” Cheney said early in her speech. She also criticized Trump for inciting the violent attack on the Capitol and said he “is not fit to lead” the country. “What January 6 shows us is that there is not an ounce of compassion in Donald Trump,” Cheney said. “He is petty, he is vindictive and he is cruel.”

She also made the case for Harris, praising the vice president for “working to unite reasonable people all across the political spectrum.”

As I’ve noted before, Cheney’s decision to campaign with Harris is not surprising, despite their party affiliations. Cheney endorsed Harris last month and her father followed soon after.