(Reuters) - P. Michael Mckinley, a diplomat who resigned last week as an aide to U.S. Secretary of State Michael Pompeo, is expected to appear on Wednesday for a closed session with the lawmakers conducting an impeachment inquiry into President Donald Trump, a U.S. official working on the inquiry said.

Reporting by Patricia Zengerle; Editing by Muralikumar Anantharaman Our Standards: The Thomson Reuters Trust Principles.