President Trump threatened on Friday to quickly revoke the security clearance of Bruce Ohr, a little-known Justice Department official, for the first time seeking to apply his power to cut access to sensitive information to a midlevel government worker rather than a prominent former national security official. Departing the White House for a fund-raiser, the president told reporters that Mr. Ohr was “a disgrace” and said incorrectly that Mr. Ohr played a part in starting the investigation into Russian election interference and possible links to Trump associates.

President Trump acknowledged publicly for the first time on Friday that  he was under investigation in the expanding inquiry into Russian influence in the election, and he appeared to attack the integrity of the Justice Department official in charge of leading it.