I don't believe any of these five theories were the principal motivating factors that lay behind Christie's decision, although of course some of them must have lurked at the back of his and Mary's minds. Christie believes — rightly in my view — that Obama became president too early after only four years in the Senate and his inexperience is showing, so he does not want to make the same error himself. By 2016 he will have a solid raft of achievements in New Jersey that he can sell to the American people, and it'll be worth noting if he starts prosecuting undocumented aliens and losing three or four stone in weight in the meantime. I believe him when he told a fan at the Ronald Reagan Library who had begged him to run: "It's extraordinarily flattering, but by the same token that heartfelt message you gave me is also not a reason for me to do it. That reason has to reside inside me." 

Cyril Connolly said that inside every fat man is a thin man trying to get out; residing inside Chris Christie is a president who is biding his time.