Former New York City Mayor Rudy Giuliani, now vice chairman of President-elect Donald Trump’s transition team, said Trump might follow through on a threat to prosecute Hillary Clinton.

Asked in ABC News interview if Trump might actually appoint a special prosecutor to investigate Clinton, Giuliani called it a “tough” question.

“As a lawyer, I hate to use the ‘on the one hand, but the other,’ but on the one hand, you don’t want to disrupt the nation with what might look like a vindictive prosecution, even though it might not be,” he said. “On the other hand, you want equal justice under the law, and if she has violated the law ― you know, the FBI never completed the [Clinton] Foundation investigation. That’s, as far as I know, that’s still an ongoing investigation. They completed the email investigation, but not the Foundation investigation.”

During the second presidential debate, Trump said that, if elected, he would instruct his attorney general to appoint a special prosecutor to investigate Clinton for her use of a private email server as Secretary of State. After a yearlong investigation, FBI Director James Comey said there was “no intentional misconduct” and recommended that no criminal charges be brought against Clinton. Trump has repeatedly attacked Clinton over the findings of the FBI probe.

If Trump followed through on his threat, Trump would be the first sitting president in recent history to use federal power to prosecute a political rival. Giuliani is now among the contenders for the role of Trump’s attorney general.

“I guess the next attorney general is going to have to figure that out. I don’t know if that will be me or not, but the next attorney general would have to figure that out,” Giuliani said.