President-elect Donald Trump has named Susie Wiles, the defacto manager of his victorious campaign, as his White House chief of staff, the first woman to hold the influential role.

Wiles is widely credited within and outside Trump’s inner circle for running what was, by far, his most disciplined and well-executed campaign, and was seen as the leading contender for the position. She largely avoided the spotlight, even refusing to take the mic to speak as Trump celebrated his victory early Wednesday morning. She resisted the formal title of campaign manager, avoiding becoming a target, given Trump’s history of cycling through people in that role.

Wiles’ hire is Trump’s first major decision as president-elect and one that could be a defining test of his incoming administration, as he must quickly build the team that will help run the massive federal government. Wiles doesn’t bring much federal government experience to the role, but has a close relationship with the president-elect.