President Donald Trump on Wednesday selected former U.S. Justice Department official Christopher Wray as FBI director to replace the fired James Comey, who will testify on Thursday on whether Trump pressed him to end a probe into a former national security adviser’s contacts with Russia.

Wray, who represented New Jersey Governor Chris Christie in the so-called Bridgegate scandal and was assistant attorney general in the Justice Department dealing with corporate fraud and financial markets cases, will need Senate confirmation to take the top job at the Federal Bureau of Investigation.

Trump’s early-morning Twitter announcement came a day before Comey was set to appear before the Senate Intelligence Committee for eagerly anticipated testimony. Some Democratic lawmakers said the president’s timing seemed designed to distract from Comey’s testimony and other congressional testimony on Wednesday.

In his first public remarks since Trump fired him on May 9, Comey is expected to be questioned about whether the president asked him during an Oval Office meeting to end the FBI’s probe into ties between former White House national security adviser Michael Flynn and Russia – part of its investigation into possible collusion between Trump’s 2016 election campaign team and Russian officials.

“I will be nominating Christopher A. Wray, a man of impeccable credentials, to be the new Director of the FBI. Details to follow,” Trump said in a Twitter message.

“It appears, obviously, that the president is trying to change the topic because we’ve got two days of hearings here that could be explosive,” Senator Mark Warner, the top Democrat on the intelligence panel, Warner told MSNBC.

On Wednesday, lawmakers will hear from Deputy Attorney General Rod Rosenstein, the No. 2 official at the Justice Department who signed a letter recommending Comey’s dismissal.