The Biden campaign is warning any presidential candidate who “calls themselves a Democrat” to refrain from repeating “discredited lies” about Joe Biden (D) and his son Hunter during the next presidential debate.

The Biden campaign is taking an aggressive stance in an effort to dismiss the mounting questions and concerns surrounding the Bidens’ business dealings in both China and Ukraine. The latter has become a particular point of interest in recent weeks, following President Trump’s phone call with Ukrainian President Volodymyr Zelensky. Democrats say Trump “pressured” Ukraine to investigate his potential rival, Biden, who played a key role in the firing of a Ukrainian prosecutor who was investigating Burisma Holdings. Hunter Biden served on the board, making $83,000 per month, despite a stunning lack of qualifications for such a position. The former vice president wanted the prosecutor fired and threatened to withhold $1 billion in aid, bragging about his ultimatum last year.

“I said, I’m telling you, you’re not getting the billion dollars. I said, you’re not getting the billion. I’m going to be leaving here in, I think it was about six hours,” Biden said during an appearance at the Council on Foreign Relations in 2018.

“I looked at them and said: I’m leaving in six hours. If the prosecutor is not fired, you’re not getting the money. Well, son of a bitch. He got fired,” he boasted.

The Biden campaign, however, is warning fellow candidates to refrain from taking a shot at the Bidens’ business dealings in China and Ukraine, and specifically the role that Hunter played.

A Biden aide warned anyone who “calls themselves a ‘Democrat’” from pushing the “discredited lies.” If they choose to do so, they “would be making a profound statement about themselves,” the aide said, according to Bloomberg.