Barstool Sports founder David Portnoy is under investigation after he threatened last week to fire “on the spot” any employee who as much as discussed unionization, according to a report.

The National Labor Relations Board has launched a probe into whether the sports site founder illegally attempted to discourage his workers from unionizing after his comments last week gained attention from Rep. Alexandria Ocasio-Cortez, according to the Hollywood Reporter.

“If you’re a boss tweeting firing threats to employees trying to unionize, you are likely breaking the law &can be sued,in your words, ‘on the spot,’” wrote Ocasio-Cortez

Portnoy’s battle with Ocasio-Cortez and other union advocates began last week when he responded to the recent formation of a union at a competing sports outlet.

“Heard @ringer employees want to unionize. Little refresher how I feel about unions,” Portnoy tweeted Monday.

He then shared an article from 2015 about workers at Gawker voting to unionize in which he writes, “I can’t tell you how much I want them to unionize. Just so I can smash their little union to smithereens.”

Rafi Letzter, who writes for Live Science, then responded: “If you work for Barstool and want to have a private chat about the unionization process, how little power your boss has to stop you, and how you can leverage that power to make your life better: my DMs are open.”

The offer prompted Portnoy to lash out. “If you work for @barstoolsports and DM this man I will fire you on the spot,” Portnoy fired back on Tuesday.

The Committee to Preserve the Religious Right to Organize then filed charging papers with the NLRB against Portnoy demanding he “tweet and otherwise publicize his severe and sincere apology.”

The filing which refers to Portnoy as a “crazed president” will require the federal agency to gather evidence and take affidavits from parties and witnesses, according to Hollywood Reporter.

But Portnoy has some choice words in response to the investigation.

“So they are suing for a heart felt apology?” he tweeted on Friday. “Is that really what I just read? How about this? Go f–k yourself. Case dismissed.”