President Biden fired Social Security Commissioner Andrew Saul on Friday amid an ongoing dispute over his leadership of the independent agency responsible for administering retirement and disability benefits.

Saul was one of the few remaining federal appointees from former President Donald Trump’s administration. The White House said he was fired after refusing a request for his resignation. Deputy Social Security Commissioner David Black was also asked to resign and he complied.

The Washington Post was first to report Saul’s dismissal. He questioned the legality of Biden’s decision in an interview with the newspaper and said he plans to be at work on Monday.

“I consider myself the term-protected Commissioner of Social Security,” Saul said.

The White House recited a list of grievances against him.

“Since taking office, Commissioner Saul has undermined and politicized Social Security disability benefits, terminated the agency’s telework policy that was utilized by up to 25 percent of the agency’s workforce, not repaired SSA’s relationships with relevant Federal employee unions including in the context of COVID-19 workplace safety planning, reduced due process protections for benefits appeals hearings, and taken other actions that run contrary to the mission of the agency and the President’s policy agenda,” a White House official said in a statement.