A combination photo shows U.S. President Donald Trump (L) in the House of Representatives in Washington, U.S., on February 28, 2017 and FBI Director James Comey in Washington U.S. on July 7, 2016. REUTERS/Jim Lo Scalzo/Pool, Gary Cameron/File Photo" width="650" height="453" data-mce-source="Thomson Reuters" data-mce-caption="FILE PHOTO: A combination photo shows U.S. President Donald Trump and and FBI Director James Comey in Washington" />(President Donald Trump and former FBI Director James Comey.Thomson Reuters)
Top Democrats from the House Judiciary Committee warned the White House that if President Donald Trump blocks former FBI Director James Comey from testifying in a hearing, they would consider it an effort to "obstruct the truth from both Congress and the American people."

The possibility of Trump invoking his executive privilege first materialized after White House counselor Kellyanne Conway acknowledged in an interview that Comey's testimony would be a "clarifying moment," but when it came to invoking executive privilege, said that "the president will make that decision."

"We write to remind you that any such assertion of privilege is almost certainly baseless, particularly given that Mr. Comey is no longer employed by the Trump Administration," the lawmakers' letter to White House general counsel Don McGahn read. "Any assertion of privilege by the President would be seen as an effort to obstruct the truth from both Congress and the American people."

"It is critical that the American public hears this testimony," the letter continued.

Comey, the FBI director who was abruptly fired by Trump in May, is scheduled to testify before the Senate Select Committee on Intelligence on Thursday. His firing was immediately met with bipartisan concern, due to his involvement in a Trump-Russia investigation that has cast a shadow over current and former members of the Trump administration.

At the public hearing, Comey is expected to answer questions that may put pressure on the embattled Trump administration, including describing the conversations Comey had with Trump regarding Russia’s interference in the 2016 US presidential election.

"Each of the relevant and ongoing investigations has focused on the question of collusion between President Trump’s campaign and the Russian government," the lawmakers wrote. "Given the manner in which Mr. Comey was dismissed, that inquiry has expanded to include questions of obstruction of justice. Mr. Comey’s testimony may shed light on government misconduct."