President-elect Donald Trump has asked U.S Rep. Michael Waltz, a retired Army National Guard officer and war veteran, to be his national security adviser, a person familiar with the matter said Monday.

The nod came despite simmering concerns on Capitol Hill about Trump tapping members of the House, where the final tally is still uncertain and there are worries about pulling any GOP members from the chamber because that would force a new election to fill the empty seat. The person spoke on the condition of anonymity to discuss the matter before Trump made a formal announcement.