The request, addressed to the top federal judge in Miami, sought to block a U.S. attorney from pursuing a politically charged inquiry before Judge Aileen Cannon, who has repeatedly decided in President Trump’s favor.
John O. Brennan at a Senate hearing in 2017. The focus of the investigation appears to be on Mr. Brennan, who helped oversee an intelligence assessment that concluded that Russia was trying to help Donald J. Trump win the 2016 election.