John McCain Was One Lucky Guy in Primary Race With Romney - Michael Barone (usnews.com):

"John McCain was one lucky guy. That has been my conclusion as we watched him beat Mike Huckabee in South Carolina January 19 by 33 percent to 30 percent, beat Mitt Romney in Florida January 29 by 36 percent to 31 percent, and then make a huge delegate sweep by winning all the winner-take-all states on Super Tuesday, February 5, including Missouri by a 33 percent-to-32 percent-to-29 percent margin over Huckabee and Romney. In California, which awarded 11 delegates to the statewide winner and three each to the winner in each congressional district, McCain beat Romney statewide 42 percent to 35 percent and carried 48 of 53 congressional districts (it appeared to be 50 of 53 before California finally counted all the votes).

Using Dave Leip's Election Atlas and the Green Papers, I calculated the delegate count if McCain's share of the vote had been exactly 3 percent less in each primary on January 19 and 26 and February 5 and if Romney's share of the vote had been exactly 3 percent more. After all, those results would have been just about as plausible, given the way the campaign and polling were going, as the actual results."