Leandra English, the acting director of the Consumer Financial Protection Bureau (CFPB), sued the Trump administration late Sunday in order to block the appointment of President Donald Trump’s pick, Office of Management and Budget Director Mick Mulvaney, as interim director of the consumer agency.

The lawsuit, English v. Trump, was filed in the U.S. District Court for the District of Columbia by English herself, not the CFPB, and seeks an injunction ordering President Trump to halt Mulvaney’s appointment to the position.

In the lawsuit, English called herself the "rightful acting director" of the CFPB. "The President’s purported or intended appointment of defendant Mulvaney as Acting Director of the CFPB is unlawful," it added.

CFPB's general counsel, Mary McLeod, has reportedly drafted a memo supporting the Trump administration's position, according to multiple sources and the White House's top spokeswoman, the American Banker reported.

Sarah Huckabee Sanders, the chief White House spokeswoman, said in a statement "the law is clear: Director Mulvaney is the acting director of the CFPB."

She specifically cited a memo by McLeod that stated the Mulvaney appointment was legitimate.

"Now that the CFPB's own general counsel — who was hired under Richard Cordray — has notified the bureau's leadership that she agrees with the administration's and [the Justice Department]'s reading of the law, there should be no question that Director Mulvaney is the acting director," Sanders said. "It is unfortunate that Mr. Cordray decided to put his political ambition above the interests of consumers with this stunt."

English had been appointed deputy director on Friday as CFPB Director Richard Cordray stepped down — a role that would be considered as acting director in the absence of a Senate-confirmed leader. However hours later, President Trump named Mulvaney as the acting director, leaving it unclear as to which of the two was the lawful head of the CFPB at this time.

The issue still remains in flux until a court makes a decision.

"The legal issues are complex enough that the leadership of the bureau is likely to remain uncertain until a court definitively resolves it," said Christopher Peterson, a law professor at the University of Utah's S. J. Quinney College of Law, and a former CFPB special adviser to Cordray.

The tussle over leadership of the CFPB has also fallen along partisan lines.

On CNN’s "State of the Union" on Sunday, Sen. Dick Durbin (D-Ill.) said he believed English was the right person to take control of the agency.

"Remember, this was the agency that fined Wells Fargo $100 million for defrauding the people who were creating phony accounts," Durbin said. "It’s a watchdog agency. Wall Street hates it like the devil hates holy water."

Sen. Lindsey Graham (R-S.C.), however, backed the appointment of Mulvaney. The CFPB is out of control, he said. "They can get into everybody’s business. I don’t think they added much at all to the consumer protection. They sure add a lot to increasing costs for midsize banks throughout the country that had nothing to do with the financial collapse."

English, who attended New York University and the London School of Economics, has served in various positions earlier within the CFPB, the Office of Personnel Management and the Office of Management and Budget.

She was also a part of a small team at the Treasury Department that helped launch the CFPB, including establishing early relationships with small banks. "It felt like we were engaging in retail politics a little bit," English said in a Washington Post interview in 2014.

"Time after time, we would go into a room, especially with community bankers, and you could just feel instantly that they were very skeptical, nervous, not expecting us to be friendly. And by the time we walked out, the tone had completely changed," she had said.

Cordray promoted her to deputy director last Friday and said she would temporarily take his place.

"Leandra is a seasoned professional who has spent her career of public service focused on promoting smooth and efficient operations. As deputy director, we will continue to benefit from Leandra’s in-depth knowledge of the operational needs of this agency and its staff," Cordray said in a statement announcing her promotion.