A slate of top House Democrats are demanding an explanation from the Trump administration bureaucrat who has refused to certify Joe Biden as the winner of the 2020 election, which is blocking the presidential transition from fully moving forward.

In a letter Thursday evening, leading lawmakers from the House Oversight and Appropriations Committees asked Emily Murphy, the chief of the General Services Administration, to brief them by Nov. 23 on why her agency has not made the official “ascertainment” that Biden won. They charged that her refusal to do so is actively impairing Biden’s ability to respond to COVID-19 and endangering national security.

“We have been extremely patient, but we can wait no longer,” the lawmakers wrote. “As GSA Administrator, it is your responsibility to follow the law and assure the safety and well-being of the United States and its people—not to submit to political pressure to violate the law and risk the consequences.” Under Murphy, a Trump administration appointee, the GSA has stated it cannot ascertain Biden as the winner because of the GOP’s challenges to the election results in court, none of which have gained traction and are backed by flimsy or non-existent evidence.