In 2005 Morris decided to sell Hunterdon Stables and became chef d'equipe of the United States show jumping team. During his term as chef d'equipe, the team won gold in the 2005 Samsung Super League, team silver at the 2006 World Equestrian Games, team gold at the 2008 Beijing Olympics, and team gold and individual gold and silver at the 2011 Pan American Games. His last competition with the United States team was the 2012 London Olympics where the team finished sixth. His term as chef d'equipe ended in 2013, when he was replaced by Robert Ridland.