Just days ahead of his meeting with one of the nation’s largest labor unions, former President Donald Trump spent part of Sunday evening and Monday afternoon attacking the leader of another major labor organization.

According to a union spokesperson, the 45th President has agreed to appear at a Teamsters Rank-and-file Presidential Roundtable alongside the labor group’s leaders on Wednesday, when he will presumably set about the task of convincing working class union members he is the 2024 presidential candidate with their interests in mind.

That didn’t prevent the former commander-in-chief from launching an attack against United Auto Workers union President Shawn Fain before he went to bed Sunday night, or stop the diatribe from continuing Monday afternoon.

“He is a real ‘STIFF’ who is selling the Automobile Industry right into the big, powerful, hands of China. 55% of the industry has already left the U.S., and the rest will soon be following if I am not elected President. He bought into Biden’s ‘vision’ of all Electric Vehicles, which require far fewer workers to make each car but, more importantly, are not wanted in large numbers by the consumer, and will ALL be made in China,” Trump wrote.

“Get rid of this dope & vote for DJT. I will bring the Automobile Industry back to our Country,” he continued.

Trump’s attack comes after the union, which represents about 150,000 auto workers in the United States, endorsed President Joe Biden’s run for a second term in the White House. Trump has since been the target of much criticism by Fain, who said the former president “doesn’t care about the American worker.”

“You know, look, when you look at these two candidates, you know, Joe Biden has a history of serving others, and serving the working class, and fighting for the working class, standing with the working class. Donald Trump has a history of serving himself and standing for the billionaire class. And that’s contrary to everything that working class people stand for,” Fain said Sunday on CBS News’ Face the Nation.

Trump managed to hold his tongue and temper through most of the day following the broadcast before issuing his response for the union to “dump” its president, but apparently Fain’s comments were still stinging his ears when he woke up Monday, because he continued along those lines that afternoon.

“Shawn Fain is a Weapon of Mass Destruction on Auto Workers and the Automobile Manufacturing Industry in the United States! Is he under contract to China, because they will be getting almost all of our ‘Car making’ Business within a very short period of time. All Autoworkers should VOTE FOR TRUMP. MAKE AMERICA GREAT AGAIN,” he wrote.

This comes as Trump is set to meet with the members of the International Brotherhood of Teamsters in Washington D.C. on Wednesday, in an effort to secure the endorsement of that — much larger — union.

“Our members want to hear from all candidates of all parties about what they plan to do for working people as President,” Teamsters General President Sean O’Brien said in a statement. “Our union wants every candidate to know that there are 1.3 million Teamsters nationwide whose votes will not be taken for granted. Workers’ voices must be heard.”

President Joe Biden has also agreed to sit with the Teamsters, a union spokesperson told the Herald, though a date has not been set for their roundtable. U.N. Ambassador Nikki Haley has been invited, but hasn’t accepted yet, the spokesperson said.