ELECTIONS ARE TOO IMPORTANT TO LEAVE TO MERE VOTERS
First, recall that you are about 1/2 a person in aggregate when you vote early.
Second, the Party itself and the media - and maybe even the candidates and often the pundits - can make big decisions about who is a frontrunner. For good or for ill, elections, afterall, are too important to leave up to mere voters, who are sixth-grade educated, superstitious, quixotic, and dangerous to the ruling class, if riled.
Look for signs of it.
Somewhere along the way, the sagacious ones decided that Obama was the best chance against the Republicans. The media started to question her about speeding up the release of records from her husband's Presidency. On the national stage, Chris Dodd said aloud that "electablity is an important issue" and said that Clinton didn't have it, on his calculus.
After that, the Candidates must have talked. The politics of "pile on" stopped, fast. Clinton gave the "team player" concession speech in Iowa.
Of course, if you read AS and (not also Bootstrapping AS), you might buy the mythology that it was all due to a dinner speech. ...
FEEL SMALL, EVEN KNOWING HOPE
So, ask yourself, is someone really competing for your vote? Or better, how much?