The US official caught in a legal battle over who should run the Consumer Financial Protection Bureau (CFPB) says she intends to spend the day at work.
Leandra English filed a lawsuit after President Donald Trump named his budget chief Mick Mulvaney acting CFPB head.
There was turmoil on Monday when Mr Mulvaney arrived at the bureau carrying a bag of donuts for staff.
A judge will rule in the coming hours or days whether Mr Mulvaney or Ms English should run the bureau.
Ms English was named acting director on Friday by outgoing head Richard Cordray, a Democrat who was appointed by the Obama administration.
But hours later, Mr Trump named his own choice of acting director. The president has been an outspoken critic of the agency, calling it a “total disaster”.
Mr Mulvaney has previously called the CFPB a “sick, sad joke” that should be scrapped.
The CFPB was set up after the 2007 financial crash to protect Americans from predatory lenders. However, Republicans say it places excessive regulatory burdens on Wall Street.
“I plan on spending the day at CFPB headquarters taking calls and meetings with external stakeholders and bureau staff,” Ms English said in a statement.
Mr Mulvaney intends to divide his time between the CFPB offices and his job as White House budget director, US media reported. It is not clear which office he was occupying on Tuesday.
A US district judge is due to hear the case later on Tuesday.
But one of the senators who helped to set up the bureau, Elizabeth Warren, said she believed the legal dispute would continue to an appeals court.
“It’s too important to everyone to let it rest at the district court,” she told Reuters.
Ms Warren led a protest rally outside the CFPB offices in Washington on Tuesday, calling for Mr Mulvaney to step aside.
There were extraordinary scenes on Monday morning when Mr Mulvaney arrived at the bureau.
He wrote in a memo to staff: “Please disregard any instructions you receive from Ms English in her presumed capacity as acting director.”
He signed off as “acting director”, urging staff to drop by his office and “grab a donut”.
Ms English had also sent agency staff a brief email on Monday, signing it: “Acting Director.”
Her lawsuit, filed on Sunday, asked a judge at a federal court in Washington DC to issue a temporary restraining order against the appointment of Mr Mulvaney.
The legal action said: “The president’s purported or intended appointment of defendant Mulvaney as acting director of the CFPB is unlawful.”
In response, the White House said the president had the authority to appoint Mr Mulvaney under the Federal Vacancies Reform Act.
But a lawyer for Ms English says the law states that as deputy director she is entitled to take power until the Senate can vote to confirm another director.
