Thomas P. Bossert, the president’s first homeland security adviser, also said part of the president’s request to Ukraine was based on a “completely debunked” conspiracy theory.
The inquiry is examining whether the employees used secure channels and the proper classification designations for what appeared to be routine emails at the time.
Details of the push by President Trump and Rudolph Giuliani for Ukraine to investigate Democrats show a sustained effort that encompassed elections in both countries.
With lawmakers headed to their districts for a two-week recess, Democrats are working on two tracks, charting their investigation and honing their message
The alarm among officials who heard the exchange between President Trump and his Ukrainian counterpart led to an extraordinary effort to keep many more people from learning about it.
“You know what we used to do in the old days when we were smart with spies and treason, right?” President Trump asked a room of American diplomats. “We used to handle it a little differently than we do now.”
The whistle-blower’s complaint accused Mr. Trump of trying to compel Ukraine’s leader to help investigate a 2020 rival, and the White House of attempting to “lock down” records of the call.