A senior former Biden administration official is appearing before House investigators on Thursday.
Ronald Klain served as former President Joe Biden's chief of staff in the first half of his term, from the beginning of his term in January 2021 until early February 2023.
He is expected to sit down with staff from the House Oversight Committee behind closed doors on Thursday morning for a voluntary transcribed interview.
Committee Chair James Comer, R-Ky., 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.
Ron Klain is the latest ex-White House official to appear in the House GOP investigation of former President Joe Biden's mental health. (Win McNamee/Getty Images )
Biden maintained he "made every decision" in a recent interview with The New York Times.
Klain is the sixth ex-White House official to appear as part of Comer's probe, and the third to appear on voluntary terms.
Former White House physician Kevin O'Connor, as well as senior advisors Annie Tomasini and Anthony Bernal, all appeared under subpoena.
Each also pleaded the Fifth Amendment to avoid answering questions.
House Oversight and Accountability Committee Chair James Comer is leading the probe. (Anna Moneymaker/Getty Images)
Ex-staff secretary Neera Tanden and longtime Biden advisor Ashley Williams both appeared for voluntary transcribed interviews, like Klain.
Both of their interviews lasted over four hours, though House GOP investigators appear to have gleaned little new information.
Before serving as Biden's chief of staff, Klain worked in the same capacity when the Delaware Democrat was vice president during the Obama administration.
He also served as a top advisor on Biden's 2020 presidential campaign.
Most critical to investigators, perhaps, is the prominent role Klain reportedly played in preparing Biden for his disastrous June 2024 debate against now-President Donald Trump.
Klain also worked for Biden during his years in the Obama administration. (Kevin Dietsch/Getty Images)
Rep. Eric Burlison, R-Mo., a member of the Oversight Committee, shared some of the information he hoped would be gleaned from Klain's sitdown.
"Did you ever see a question of cognitive ability in the president? Were you aware that he was not making these decisions? Was he being led?" Burlison asked.
Fox News Digital's Deirdre Heavey contributed to this report.