Ed Muskie, U.S. senator from Maine at the time, was considered the Democratic front-runner because he polled the best out of a crowded field, and at least one poll had shown him leading Nixon. But he wasn't that popular with the left of the party, and there were a couple of political behemoths to the right of him (Hubert Humphrey, George Wallace). Muskie won Iowa and New Hampshire, but his margin of victory was unimpressive in both, which set up a devastating Florida primary where he spent loads of money but finished a disastrous fourth with only 9% of the vote (Alabama governor George Wallace won big by courting the NASCAR vote).
After Florida Muskie was devastated. And this is where the crazy impossibility happens. Thompson writes:
"...Muskie called a meeting the day after the primary to announce that he was quitting the race. [Muskie's staffers] had managed to talk him out of it, agreeing to work without pay until after Wisconsin, but when word of the candidate's aborted withdrawal leaked out to the press ... well, that was that. Nobody published it, nobody mentioned it on TV or radio -- but from that point on, the only thing that kept the Muskie campaign alive was a grim political version of the old vaudeville idea that 'the show must go on.'"
Muskie went on to win Illinois a couple of weeks later, and at one time he polled even with Hubert Humphrey for the lead in the crucial Wisconsin primary that year, but George McGovern pulled off a surprise win in that Wisconsin primary and went on to take the nomination. The fact that Muskie survived for another month before dropping out would not have been possible today. There is no way that in today's media environment someone would get word of that meeting where the former frontrunner announced he was quitting and just sit on it. Let alone a whole traveling pack of campaign trail journalists sitting on what would be a candidate-killing story. It was the first campaign trail anecdote I read that basically reached out and slapped me in the face with its shocking foreignness. It surprised me so much I had to write about it here.