Ex-President Joe Biden’s former chief of staff ignored reporters on his way out of an interview with congressional investigators on Thursday after a marathon grilling behind closed doors.

Ronald Klain served as White House chief of staff for the first half of Biden’s term. He also reportedly played a key role in helping the former leader prepare for what proved to be a disastrous first and only 2024 election debate against current President Donald Trump.

Klain sat with staff and some lawmakers on the House Oversight Committee for hours for a voluntary transcribed interview.

Committee Chair James Comer, R-Ky., earlier told reporters that the interview was going well just after the session broke for lunch.

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“I think we’re having a very good transcribed interview. Mr. Klain is being fairly responsive to our questions,” Comer said.

Comer is investigating whether Biden’s top White House aides concealed signs of mental decline in the then-president, and if that meant executive actions were signed via autopen without his knowledge.

Lawmakers who briefly attended the interview, however, called him “credible.”

“I think he is telling what he knows accurately,” Rep. Andy Biggs, R-Ariz., told Fox News Digital.

On the other side of the aisle, Rep. Ro Khanna, D-Calif., told reporters, “He answered every single question. He was fully cooperative.”

Comer was guarded, however, in response to questions about how much new information was gleaned.

“There have been tidbits,” he said. “We’ve asked specific questions. Obviously, evidence emerges on a daily basis that would suggest Joe Biden wasn’t mentally fit to be President of the United States.”

Klain is the sixth former Biden administration aide to appear for Comer’s probe and the third to appear voluntarily.

Former White House physician Kevin O’Connor, as well as senior advisors Annie Tomasini and Anthony Bernal, all appeared under subpoena.

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Each also pleaded the Fifth Amendment to avoid answering questions.

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Longtime Biden aide Ashley Williams and former staff secretary Neera Tanden both appeared voluntarily.

Like the previous five before him, the longtime Democratic operative did not answer questions from reporters either before or after his interview.