Steve Schmidt, the combative Republican given the job of revamping John McCain’s faltering presidential campaign, has a Democrat to thank for catapulting him into the big league of US political strategists.

Late in 2005, Maria Shriver, the wife of Arnold Schwarzenegger, California governor, led an overhaul of her husband’s staff as he prepared for a tough re-election battle. Ms Shriver, niece of John F. Kennedy and a lifelong Democrat, recommended Mr Schmidt to run the campaign. It turned out to be a wise choice as “The Governator” bounced back from a 33 per cent approval rating to win by a landslide.