Deputy Attorney General Rod Rosenstein on Tuesday dismissed a new effort by members of the House Freedom Caucus to impeach him, sending a sharp message to his critics that the Justice Department is not going to be “extorted.”

Speaking to an audience at the Newseum, Rosenstein, who has been repeatedly attacked by President Donald Trump amid the ongoing Russia investigation, pointed to the members’ failure to sign their draft articles of impeachment as evidence that the latest threat against him has no real merit. “They can’t even resist leaking their own drafts,” he laughed, contrasting the different processes Justice Department officials and House Freedom Caucus members take when issuing such documents.

“That’s the way we operate, we have people who are accountable,” said Rosenstein, who oversees special counsel Robert Mueller’s investigation into Russian meddling in the 2016 election following Attorney General Jeff Sessions’ recusal. “And so I just don’t have anything to say about documents like that that nobody has the courage to put their name on and that they leak in that way.”

He continued, “There have been people who have been making threats privately and publicly against me for quite some time. And I think they should understand by now the Department of Justice is not going to be extorted. We’re going to do what is required by the rule of law and any kind of threats that anybody makes are not going to affect the way we do our jobs.”

The House Freedom Caucus’ reported effort to impeach Rosenstein comes amid mounting fear that Trump will seek to remove Rosenstein or Mueller as the Russia investigation moves closer to the president’s business dealings. Freedom Caucus chair Rep. Mark Meadows confirmed the draft, calling it a “last resort” strategy if the department refuses to hand over requested documents related to the investigation.