President Trump selected Mulvaney, director of the Office of Management and Budget, to run the agency on an interim basis. However, before he left office former Director Richard Cordray designated his deputy, Leandra English, as acting director. She has sued Trump over the issue and asked for an injunction prohibiting Mulvaney from serving.

While that battling is raging, Mulvaney on Monday operated as acting director of the agency.

CUNA officials said they were encouraged by Mulvaney's first moves.

"We're pleased to see the bureau halt rulemaking activities for time being, as we've been pushing for an end to burdensome rulemakings since the start of the new administration," said Ryan Donovan, CUNA's chief advocacy officer. "While credit unions do not want more new rules and requirements, they do need fixes for current rules that are burdensome for credit unions, and more exemptions where possible, and CUNA looks forward to working with the bureau to get those fixes moving forward for the benefit of consumers."

Meanwhile, English and the Trump Administration are battling in federal court over agency leadership. Cordray and English contend that Dodd-Frank states that the deputy director serves as director in the absence or unavailability of the director.

The administration argues that the Federal Vacancies Act states that the president can make an interim appointment to the agency as long as the person appointed has been confirmed by the Senate for another position.

In its response to the lawsuit filed Monday night, the administration accuses Cordray and English of using a "bureaucratic sleight-of-hand" to have English appointed.

"Legally, [English] never acceded to the position of Acting Director because the President's designation of Acting Director Mulvaney took effect immediately upon the former Director's resignation," the administration said.

On Monday, 26 current and former Democratic members of Congress filed a brief that sided with English.

The members—including House Democratic Leader Nancy Pelosi of California and Senate Democratic Leader Charles Schumer of New York—said that Dodd-Frank was designed to ensure the agency's independence. In addition to the current members, former Democratic Rep. Barney Frank of Massachusetts—a primary co-sponsor of the law that bears his name—was among those filing the brief.

"Only that structure is consistent with the independence, that was so central to Congress's design in establishing the Bureau as a primary protector for American consume," the Democrats said.