WASHINGTON (AP) — The special counsel investigating the origins of the FBI's probe into the 2016 election now has the authority to use classified information indefinitely in his investigation, a procedural step following his earlier appointment, according to a memorandum issued by President Donald Trump.

Outgoing Attorney General William Barr named U.S. attorney John Durham as a special counsel in the investigation into the origins of the FBI's probe of the 2016 election. Durham was already leading an investigation, but the appointment makes it more difficult for the new attorney general to close it. The FBI's probe morphed into former special counsel Robert Mueller's investigation of possible Trump-Russia cooperation.

The ongoing Durham investigation followed Trump's repeated calls to "investigate the investigators." In May 2019, Trump directed U.S. intelligence officials to assist in that review and gave the attorney general permission to declassify or downgrade information or intelligence that relates to his review.

Trump's memo came Tuesday as he continues to propel his claims that the Russia investigation that shadowed his presidency was a "witch hunt." It's the latest example of efforts by Trump officials to use the final days of his administration to essentially box President-elect Joe Biden in by enacting new rules, regulations and orders designed to cement the president's legacy.

Barr earlier told The Associated Press that he was naming Durham as special counsel in what turned out to be one of his final moves as attorney general. He resigned last week and his deputy Jeffrey Rosen is taking over on Thursday. The move added a wrinkle for whomever Biden nominates as attorney general, especially because Democrats have dismissed Durham's probe.

Also on Tuesday, Trump appointed Ezra Cohen, of the District of Columbia, to chair the Public Interest Declassification Board. Cohen, a Trump loyalist, currently is acting undersecretary of defense for intelligence.

The board advises the president about issues pertaining to national classification and declassification policy. Created by Congress, the board is tasked with promoting robust public access to materials that document U.S. national security decisions and activities.