“Tom has never talked with any foreign individual or entity for the purposes of raising money for or obtaining donations related to either the campaign, the inauguration or any such political activity,” said Owen Blicksilver, a spokesman for Mr. Barrack. The inaugural committee focus was reported earlier on Thursday by The Wall Street Journal.

The super PAC, Rebuilding America Now, was formed in the summer of 2016 when Mr. Trump’s presidential campaign was short of cash and out of favor with many major Republican donors. While Mr. Trump insisted that he could finance his own campaign, he refused to dig too deeply into his own pockets.

According to several of the people familiar with the investigation, Paul Manafort, who then headed the campaign, suggested that Mr. Barrack step into the void by creating and raising funds for the political action committee, which could collect unlimited amounts of money as long as it avoided coordinating closely with the candidate.

In an interview with investigators a year ago, Mr. Barrack said that Mr. Manafort seemed to view the political committee as an arm of the campaign, despite laws meant to prevent such coordination, according to a person familiar with the interview.

Federal election law requires a cooling-off period of at least 120 days before campaign staff members join a political committee backing the same candidate, but Mr. Manafort dispatched two friends from the campaign, Laurance Gay and Ken McKay, to run the operation. A press officer said at the time that the committee violated no rules because the campaign never paid the two men. Neither man returned repeated phone calls seeking comment.