The battle over who will lead the federal government’s top consumer financial watchdog agency is now headed to court.

The extraordinary fight, which intensified on Sunday night, adds to the uncertainty over the fate of the Consumer Financial Protection Bureau, a regulator created in the aftermath of the global financial crisis of nearly a decade ago. It encapsulates dueling visions of how the American financial system could be regulated, as President Trump moves to loosen regulation created under the Obama administration to rein in the financial industry.

Leandra English, the deputy director of the bureau who was set to become its temporary chief, filed a lawsuit late Sunday night to block Mr. Trump’s choice of someone else from taking control of the agency on Monday morning.