Larry Sabato on how Kerry did it:
John Kerry was as dead as the proverbial doornail in 2003 after he lost his frontrunner status, faded even in his own backyard, and fired his campaign manager. Yet John F. Kerry has become John L. Kerry, with the “L” standing for Lazarus. Short of a religious miracle, how did he do it? Another L word: LUCK. Yes, he’s experienced, understands the nuances of politics, has a great life story, and all the rest. So do other candidates. But Kerry’s timing was impeccable. He rose as Dean fell, just as Democrats were looking for a substitute for their near-nominee, just as a Vietnam veteran–honest, unprompted, and unscripted–emerged into the klieg lights to tell spellbound Iowans how a young John Kerry heroically risked his own life to save his fellow soldier’s in the nightmare that was ‘Nam.
But you have to admit, Kerry made a lot of his own luck, by successfully changing the tone of his campaign in the two weeks before Iowa.