The Trump White House had been considering Robert Mueller III as a top candidate to lead the FBI before the deputy U.S. attorney general changed course and tapped Mueller to serve as special counsel investigating Russian interference in last year’s election, two sources familiar with the process told NPR.

Mueller had gone so far as to meet with Justice Department leaders and White House officials about the FBI job, which opened after President Trump fired Director James Comey in a surprise May 9. But that idea went by the wayside after Deputy Attorney General Rod Rosenstein instead reached out to Mueller to run the politically sensitive Russia probe, which is also examining ties between Russians and Trump campaign aides, the sources said.

Mueller has long been considered one of Washington’s most indispensable men. He served in top roles at the Justice Department and became President George W. Bush’s FBI director only days before the September 11, 2001, attacks devastated the country.