Matthew G. Whitaker, the acting attorney general, was paid more than $1.2 million in the past few years by a group active in conservative politics that does not reveal its donors, according to financial disclosure statements released Tuesday and other documents.

The disclosure raised questions about who Mr. Whitaker’s financial patrons had been before he joined the Justice Department last year and whether he might have any undisclosed conflicts of interest. And it highlighted the prominence of so-called dark money groups that pursue political agendas and employ members of both parties without being required to make public the source of their funding.

Mr. Whitaker worked for nearly four years as the executive director of the group, the Foundation for Accountability and Civic Trust, also known as FACT, before being tapped as chief of staff for Jeff Sessions, then the attorney general, in September 2017. Mr. Whitaker became acting attorney general this month after Mr. Sessions was forced out….

The group provided the overwhelming majority of his income since at least 2016, according to the fi\

Mr. Whitaker also faced new questions on Tuesday about donations to his unsuccessful 2014 campaign for a United States Senate seat in Iowa. Mr. Whitaker’s campaign committee received four donations totaling $8,800 this year, a few months after he joined the Justice Department, records show.

Executive branch officials are generally prohibited by a federal law, the Hatch Act, from knowingly soliciting or accepting campaign donations….

“I don’t see Matt Whitaker ever playing the role of anybody’s bag man or errand boy,” Mr. Gustoff said. He said that Mr. Whitaker “might possibly” know the identities of FACT’s donors, but added that Mr. Whitaker “would do what he thinks is right regardless of whether somebody funded an activity he was involved in or not.”