WASHINGTON—Sen. Elizabeth Warren is pressing the Consumer Financial Protection Bureau over what arrangements the agency has made to ensure that acting Director Mick Mulvaney is excluded from decisions that affect banks and other firms that previously gave him campaign contributions.

In a letter to Sonya White, the agency’s ethics official, the Massachusetts Democrat asked for details on what matters Mulvaney is recused from following comments he made earlier this week in which he said campaign contributions were a key factor in whether he took meetings with lobbyists.

“After Mr. Mulvaney's recent comments about the pay-to-play culture he maintained in his congressional office, I'm eager to learn more about safeguards the CFPB put into place to ensure that Mr. Mulvaney was excluded from decisions that affected the financial institutions that had given him campaign contributions,” Warren said in a letter to White dated Thursday.