White House homeland security advisor Tom Bossert resigned Tuesday, just one day after John Bolton took over as national security advisor, and two days after National Security Council spokesman Michael Anton quit.

Bossert, who appeared on television as recently as this weekend to defend the administration’s border-security policies, resigned at Bolton’s request, multiple outlets have reported.

“The President is grateful for Tom’s commitment to the safety and security of our great country. Tom led the White House’s efforts to protect the homeland from terrorist threats, strengthen our cyber defenses, and respond to an unprecedented series of natural disasters. President Trump thanks him for his patriotic service and wishes him well,” White House Press Secretary Sarah Huckabee Sanders said in a statement.

Bossert was initially brought in to monitor the activities of former national security advisor Michael Flynn but quickly transitioned to overseeing natural disaster response, according to Axios. He was reportedly well liked by senior White House officials and the president himself, prompting speculation that his ouster is part of Bolton’s efforts to streamline the foreign-policy messages Trump receives from staff.