And no evidence has emerged showing that Mr. Ohr or his wife played a role in starting the F.B.I.’s Russia investigation. Rather, it was contacts between a former Trump foreign policy adviser, George Papadopoulos, and Russian intermediaries that prompted the bureau to open the inquiry in late July 2016.

But Mr. Trump has embraced the theory, casting Mr. Ohr and his wife as central players in what he calls the “rigged witch hunt” and accusing the couple of having what he claims are indirect contacts with Russians — apparently a reference to Mr. Steele’s research.

“They should be looking at Bruce Ohr and his wife, Nellie, for dealing with, by the way, indirectly, Russians,” Mr. Trump said as he boarded Marine One for a fund-raising trip to the Hamptons. Asked about Mr. Ohr’s security clearance, Mr. Trump added: “I think Bruce Ohr is a disgrace. I suspect I will be taking it away very quickly.”

A lawyer for Mr. Ohr, Joshua Berman, did not immediately respond to a message seeking comment.

Former Justice Department officials said that it should be up to the department and its inspector general, Michael E. Horowitz, to determine whether Mr. Ohr’s contact with Mr. Steele was improper. It is “not a matter to be judged by the president without Justice Department and inspector general input,” said Eugene Casey, the former chief of the F.B.I.’s Eurasian Organized Crime Unit.

Mr. Casey said that he worked closely with Mr. Ohr in 2005 and 2006, when Mr. Ohr led the department’s organized crime unit. “I knew Bruce to be a man of integrity,” Mr. Casey said. “Bruce was a committed partner in the F.B.I.’s struggle to counter Russian organized crime in the U.S. and abroad.”

A largely anonymous part of the 113,000-person Justice Department work force, Mr. Ohr, who did not work on counterintelligence, has not been found to violate the terms of his security clearance. He was given a title demotion this year from his role leading the counternarcotics unit and works in the criminal division on smaller legal matters. A Justice Department spokeswoman would not comment on Mr. Ohr, including on why he lost his more senior title.

“Without clearance, Bruce could lose his job,” said Julie Zebrak, the former deputy chief of staff to James M. Cole, the deputy attorney general under President Barack Obama.