Senate Minority Leader Chuck Schumer said Wednesday that the Justice Department official who wrote the memo justifying the firing of former FBI Director James Comey should have nothing to do appointing a special prosecutor to probe Russia’s influence on the U.S. election.

Deputy Attorney General Rod Rosenstein recommended Comey’s ouster to Trump, and is leading the investigation into Russia’s influence in the U.S. election. But Schumer said Rosenstein can’t be trusted to pick an objective special prosecutor.