Trump slams FBI, DOJ leadership ahead of expected GOP memo release But the “Rank & File are great people," the president tweeted this morning.

 -- President Trump today attacked the top leadership of the FBI and the Justice Department, accusing them of politicizing the “sacred investigative process” as he’s expected to authorize the release of a controversial Republican memo accusing the DOJ of political bias.

“The top Leadership and Investigators of the FBI and the Justice Department have politicized the sacred investigative process in favor of Democrats and against Republicans - something which would have been unthinkable just a short time ago,” Trump tweeted early this morning.

The “Rank & File are great people,” he added, one day after the union representing FBI agents issued a strong statement in support of FBI Director Christopher Wray.

"The FBI Agents Association appreciates FBI Director Chris Wray standing shoulder to shoulder with the men and women of the FBI as we work together to protect our country from criminal and national security threats,” the statement Thursday read.

The FBI declined to comment on this morning's tweet.

Trump, who has previously expressed support of the publication of the memo, read the four-page document Wednesday, sources told ABC News. The White House is expected to inform the committee today that its review process is complete and that the administration has no objection to the release of the memo. White House Chief of Staff John Kelly met Wednesday with five career FBI officials to review the memo.

The memo accuses the Justice Department of acting inappropriately when it sought a surveillance warrant in October 2016 for a former Trump campaign adviser suspected of being a Russian agent, sources told ABC News.

Despite “grave concerns” expressed by the FBI, it will be up to the House Intelligence Committee to determine the exact timing of the release of the memo, administration and congressional sources said. Trump ignored questions from reporters Thursday about Director Wray’s concerns over the memo and whether the president trusted his judgment.

Sen. James Lankford, R-Okla., expressed support for the FBI director, saying Wray is “handling the pressure well.”

“There’s no FBI director that hasn’t faced undue political pressure,” Lankford added.

House rules do not clearly lay out how the memo would be made public but sources familiar with the process told ABC News they expect it to be released today after the committee receives notice from the White House. The memo could be entered into the Congressional Record when the House is back in session today at 4:30 p.m., barring any changes to the floor schedule.