WASHINGTON – President Trump will nominate former Justice Department official Christopher Wray for FBI director to replace James Comey, who was abruptly fired last month as he conducted an investigation into possible collusion between Trump campaign associates and Russia.

The president made the announcement early Wednesday morning via Twitter.

"I will be nominating Christopher A. Wray, a man of impeccable credentials, to be the new Director of the FBI," Trump tweeted. "Details to follow."

A former chief of the Justice Department's Criminal Division from 2003 to 2005, Wray served during the administration of President George W. Bush. During his time in the government, Wray was a member of the administration's Corporate Fraud Task Force and oversaw the fraud prosecutions of former executives at Enron Corp.

Now in private practice, Wray is a personal attorney for New Jersey Gov. Chris Christie, a major supporter of Trump who is often mentioned as a possible future high-ranking administration post.

If confirmed by the Senate, Wray would take over a job with global responsibilities. But the most prominent ongoing FBI investigation — the investigation into whether Trump associates coordinated with Russians trying to influence the 2016 presidential election by hacking Democrats — will continue to be managed by the Justice Department’s special counsel Robert Mueller.

Mueller, a former FBI director, was appointed to lead the Russia investigation last month following Comey's May 9 dismissal. Various congressional committees are also investigating.

Trump made the announcement a day before former director Comey is due to testify about the Russia investigation and the circumstances behind his dismissal.

Comey is expected to say that Trump asked him to ease up on an investigation of former national security adviser Michael Flynn, who is involved in the Russia probe, and refute Trump’s previous assertions that Comey assured him three times that the president was not a subject of the FBI’s wide-ranging investigation, according to a person familiar with his actions.

"The president is trying to change the topic," said Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee on MSNBC. While Warner said he didn't know Wrap personally, he noted the former Justice official has a good reputation.

After a search that focused on political figures – including former U.S. Sen. Joe Lieberman – Trump went with a law enforcement professional for the post.

Wray is a partner in the law firm of King & Spalding, overseeing the firm’s government investigations practice. The unit represents companies and individuals in white-collar criminal and regulatory enforcement matters.

Ken Wainstein, former chief of the Justice Department’s National Security Division, described Wray as “an exceptionally strong choice.’’

“Chris Wray has an excellent record of public service,’’ said Wainstein, who also had been a candidate for the top FBI job. “He has seen the job and the Justice Department in all its missions. He was a line prosecutor. And he oversaw the Justice Department’s Criminal Division in the aftermath of 9/11, which is critical to deal with the counter-terrorism challenges that exist now.’’