“We had a hierarchy in my office in Congress,” Mr. Mulvaney, a former Republican lawmaker from South Carolina, told 1,300 bankers and lending industry officials at an American Bankers Association conference in Washington. “If you’re a lobbyist who never gave us money, I didn’t talk to you. If you’re a lobbyist who gave us money, I might talk to you.”

At the top of the hierarchy, he added, were his constituents. “If you came from back home and sat in my lobby, I talked to you without exception, regardless of the financial contributions,” said Mr. Mulvaney, who received nearly $63,000 from payday lenders for his congressional campaigns.