Lisa Gordon-Hagerty resigned as administrator of the Department of Energy’s National Nuclear Security Administration after two years, eight months and 22 days as the head of the U.S. civilian nuclear weapons program, the agency announced Friday.

The official statement gave no reason for the departure, which happened days after the still-unsettled U.S. election. At deadline, Democratic nominee Joe Biden, the former vice president, led President Trump in key battleground states that hadn’t been called for one candidate for the other. 

Gordon-Hagerty, the first woman to lead the National Nuclear Security Administration (NNSA), was confirmed Feb. 15, 2018. An outspoken Trump supporter, she was the fifth Senate-confirmed NNSA administrator in history. Last year, she told sister publication

Nuclear Security & Deterrence Monitor that she would strongly consider staying in government service if Trump won a second term.

Gordon-Hagerty joined the Trump administration after consulting for a while. Before that, she worked for Centrus, the nuclear fuel broker and centrifuge technology developer that used to be the government-owned U.S. Enrichment Corp. Before Centrus, she logged staff stints with the National Security Council, the Department of Energy and Congress.

Defense News was the first to report Gordon-Hagerty’s departure. The publication said Gordon-Hagerty resigned over intractable tensions with Secretary of Energy Dan Brouillette. Last winter, the two disagreed about the NNSA’s budget, with Gordon-Hagerty preferring the roughly $20 billion Congress ultimately approved and Brouillette arguing for a smaller number.

William Bookless, Gordon-Hagerty’s deputy, became acting NNSA administrator on Friday, according to the NNSA’s statement.