Former FBI Director James Comey is set to testify before the House Judiciary and Oversight Committee Friday after months of resisting their request to do so.
The committee subpoenaed Comey last month to testify about investigations into the Donald Trump campaign's alleged ties to Russia and Hillary Clinton's emails.
Comey had argued that the GOP led investigation in the decision-making by the FBI and the Justice Department in 2016 and 2017 was politically motivated.
Call for public setting
He said in a Thanksgiving Day tweet that he may not appear if the interview is not conducted in a public setting.
"I'm still happy to sit in the light and answer all questions. But I will resist a 'closed door' thing because I've seen enough of their selective leaking and distortion." Comey added: "Let's have a hearing and invite everyone to see."
But Comey relented to the closed-door interview after gaining a promise that a transcript of the session would be released to the public after 24 hours.
Republican lawmakers maintain that anti-Trump bias among senior officials resulted in the FBI focusing more on its probe into the Trump campaign's links to Russia and less on its investigation into Democratic candidate Clinton's private email server.
Trump has repeatedly called the Russia probe a "witch hunt" and has accused Comey and his close colleagues of being corrupt.
Democrats complain Republicans are simply trying to fuel a conspiracy theory to protect Trump from the ongoing Russia probe led by special counsel Robert Mueller.
Democrats say they will scrutinize Trump's attacks on the FBI and the Justice Department when they assume control of the House in January. They have also urged their Republican counterparts to shield Mueller from any attempts by Trump or his newly-appointed acting attorney general, Matthew Whitaker, to impede the investigation.
Wayne Lee contributed to this report.