This union leader openly challenged Donald Trump. So Trump went after him—with grave consequences.

If we know anything by heart at this point, it’s that the president-elect isn’t one to let it slide when he feels he’s been wronged. But it was still surreal to see Donald Trump attack a local union leader by name to his audience of 17 million on Twitter.

Trump blasted out this one-two punch on Wednesday night:

Jones is a union leader in Indianapolis who represents workers at the Carrier plant where Trump rolled through last week, trumpeting his victory in saving their jobs. Although Trump’s campaign trail promise was to save all of the factory’s 1,350 jobs, the president-elect said he convinced the company to keep 1,100 jobs in Indiana rather than moving to Mexico. But according to the Washington Post, the actual number is closer to 800 union jobs saved, with Trump taking credit for saving another 350 jobs that weren’t going anywhere in the first place.

Meanwhile, 550 workers are still losing their jobs. For their trouble, United Technologies, Carrier’s parent company, will receive $7 million in tax breaks over the next decade.

All those machinations were enough for Jones, the United Steelworkers leader, to proclaim that Trump “lied his ass off” about the number of jobs that would be saved.

Jones clearly touched a nerve, and he’s already dealing with the fallout of having his name smeared as the leader of a “terrible” union before millions of people.

As the Post reported late Wednesday night, Jones’ phone started blowing up, with random, threatening callers asking what kind of car he drives and saying, “We’re coming for you.”

Jones said the union wasn’t even involved in negotiations with the company, which is still shipping 700 factory jobs to Mexico.

For now, Jones is focused on raising the spirits of the 3,000 workers he represents, and told the newspaper that he doesn’t have time to waste worrying about Trump.

“He needs to worry about getting his Cabinet filled and leave me the hell alone,” he said.

Trump’s openly antagonizing union leaders could be a harbinger of ominous things to come. And if the billionaire makes his disdain for labor unions a cornerstone of his new administration, he’ll be in very bad company.