The White House could announce new leadership for the National Nuclear Nuclear Security Administration before September is out, a source said Thursday.

Frank Klotz, the current undersecretary for nuclear security and National Nuclear Nuclear Security Administration (NNSA) administrator, has said privately his successor could be announced by the end of the month, according to an insider with knowledge of the conversation.

Klotz, a retired Air Force lieutenant general, was appointed by then-President Barack Obama in 2014. He has remained at his post as head of the Energy Department’s quasi-independent nuclear stockpile steward well into the first year of the Donald Trump administration — despite rumors that he expected to depart the civil service before Inauguration Day.

It remains unclear who would succeed Klotz, though the same source who revealed the administrator’s supposedly imminent departure said the White House’s top choice for the job, Lisa Gordon-Hagerty, is still in the running.

Gordon-Hagerty is a former physicist at the Lawrence Livermore National Laboratory in California who served at DOE headquarters for six years during the 1990s in two senior roles: director of the Office of Emergency Response, where she led efforts on emergency readiness and response for nuclear or radiological incidents; and acting director of the Office of Weapons Surety, lead official for ensuring the safety and security of the U.S. nuclear arms program.

She subsequently moved to the National Security Council staff as director for combatting terrorism, and then into the private sector. Gordon-Hagerty, currently founder and CEO of the nuclear- and national security-focused LEG Inc. consulting firm, has declined to comment on her anticipated nomination to head the NNSA.