With doughnuts in hand, President Donald Trump's pick to head the U.S. government consumer watchdog agency turned up for work on Monday, challenging the acting appointee of the Obama-era leader in an partisan showdown over how the U.S. financial system should be regulated.

Mick Mulvaney, the White House budget chief, was named acting director of the Consumer Financial Protection Bureau (CFPB) by Trump last week. But Mulvaney, who tried to dismantle the agency when he served in the U.S. House of Representatives, faced a challenge from Leandra English, who had been named temporary head of CFPB by outgoing director Richard Cordray.

Mulvaney and English both issued statements on Monday morning indicating they were in charge of the 1,600-employee CFPB.