James Comer, R-Ky., the chairman of the House Oversight Committee, is demanding that three top White House aides appear before his panel later this month to discuss President Joe Biden’s mental fitness. 

Comer, who is leading an impeachment inquiry into Biden that has yet to yield any evidence of wrongdoing, issued subpoenas on Wednesday to Anthony Bernal, a top adviser to first lady Jill Biden, Annie Tomasini, White House deputy chief of staff, and Ashley Williams, a senior adviser to the president requesting they sit for depositions.

In letters sent to the three staff members, the GOP committee chair claimed that the aides may be “running interference on behalf of the President and perhaps doing some of the President’s job for him.”

“President Biden is clearly unfit for office, yet his staff are trying to hide the truth from the American people,” Comer charged in a separate statement. “Key White House staff must come before our committee so we can provide the transparency and accountability that Americans deserve.” 

News of the subpoenas was first reported by Axios. In a statement, White House spokesperson Ian Sams told Axios: “Like everything Congressman Comer has done over the past year, these subpoenas are a baseless political stunt intended for him to get media attention instead of engage in legitimate oversight.”

The letters ask the staff to respond to the subpoenas by July 17. 

The president’s health and cognitive fitness have been in the spotlight since last month’s debate, in which Biden, 81, appeared to be low energy and at times stumble and lose his train of thought. His performance sparked concern within the Democratic party about Biden’s ability to defeat former President Donald Trump in November and led to calls from some for the president to drop his bid. 

As of Thursday, nearly a dozen sitting Democratic members from both chambers of Congress have publicly called on Biden to exit the 2024 race. The president has been steadfast in his intent to stay the course and has been on a campaign to shore up support, recently speaking with Democratic mayors, governors, the Congressional Black Caucus, union leaders, top donors and more. 

Biden faces what is seen as a key test Thursday evening, when he is set to hold a rare solo press conference at the conclusion of the NATO summit in Washington.