Both sides appeared to be preparing for a fight Saturday, including wading into the fine print of federal rules to bolster their position. The Justice Department’s Office of Legal Counsel issued an eight-page opinion late in the day supporting Mulvaney’s appointment as temporary head of the agency, while other legal analysts called the move illegal.

“We think the clear legal authority is that the president does have this authority. We’ll find out based on how Ms. English decides to act at the appropriate time,” a senior administration official said in a call with reporters.

In a brief interview Saturday, Cordray disagreed. “The law authorized me to appoint a deputy director, and I did so. My understanding of the law is that the deputy director serves as the acting director upon my resignation. If there are disagreements about these issues, the appropriate place to settle them would be in the courts,” he said.