Actress Natascha McElhone has reportedly left the main cast of ABC's 'Designated Survivor' for a main role on the upcoming Hulu program 'The First'. The show, which is being executive produced by by ?House of Cards? creator Beau Willimon, focuses on the first human mission to Mars and the challenges astronauts face in their journey towards interplanetary colonization. Since 'Designated Survivor' debuted last fall, McElhone has starred as Alex Kirkman, the wife to Kiefer Sutherland's Tom Kirkman. According to sources, McElhone will finish her commitment for production on ?Designated Survivor's' second season and then move on to ?The First."