Donald Trump says Hillary Clinton would be in jail if he were president of the United States, something no major political party nominee has said about his opponent in American history.

The statement came during Sunday night’s town hall-style debate, during an exchange about Clinton’s emails. “When you talk about apology, I think the one that you should really be apologizing for and the thing that you should be apologizing for are the 33,000 emails that you deleted and that you acid-washed,” he said.

Clinton smiled while Trump talked.

“I didn’t think I’d say this, but I’m going to say it, and I hate to say it, but if I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation,” he said as she seemed to laugh internally at the very idea of him being elected. “There has never been so many lies, so much deception, there has never been anything like it, and we’re gonna have a special prosecutor.”

Clinton responded, “It’s just awfully good that somebody with the temperament of Donald Trump is not in charge of the law in our country.”

Trump nodded and pouted angrily. “Because you’d be in jail,” he said.

In response to the exchange, Eric Holder, the U.S. attorney general from 2009 to 2015, tweeted, “So @realDonaldTrump will ORDER his AG to take certain actions-When Nixon tried that his AG courageously resigned. Trump is dangerous/unfit.”

At Trump rallies around the country and during the Republican National Convention in Cleveland in July, “lock her up!” chants have proven popular among Trump devotees.

Sunday marks the first time Trump has elevated those chants to the level of official policy.