Testifying before the House Intelligence Committee, he defended his decision to take the complaint to the White House first.
Joseph Maguire is the acting director of national intelligence, and his political skills are being put to the test.
The move comes after the Republican-controlled Senate passed a non-binding resolution calling for its release.
A U.S. intelligence official's concerns about Trump's "promises" to a foreign leader involve Ukraine, The Washington Post reported.
The NYT says a complaint to top intelligence community officials about alleged conduct by the president involves more alleged incidents than first reported.