The Clinton-Obama contest is like a 15-round heavyweight title bout in boxing.

Hillary went for an early knockout. All previous Democratic races since 1960 have been decided that way, with one candidate winning decisive primaries, forcing his opponents to withdraw. But Obama beat her to the punch in Iowa, survived a loss in New Hampshire, and countered her sweep of New York, New Jersey and California on Super Tuesday by winning a large number of smaller states, largely by out-organizing Hillary in caucus states. While most traditional candidates are forced out if they lose key states because their money dries up, Obama’s ingenious use of Internet funding provided him with an ample financial base even as he fell behind Hillary in the delegate count.

But Hillary, in spending all her resources on an early Super Tuesday knockout, was too depleted to do well in the middle rounds — the February caucus and primary states. Her focus on an early knockout led her to neglect organizing in these states, and her insistence on spending every dime she had in pursuit of an early win left her financially incapable of competing in these February contests. Obama won round after round on points, sweeping 11 states in a row and establishing a solid lead in elected delegates.

Obama piled up such a lead in points in the middle rounds that Hillary has been forced to go for a knockout in the final rounds. Knowing that Obama has more delegates, she has to win decisively in the late primaries to have a chance at persuading the superdelegates to flip and abandon the voters’ choice. But, so far, the proportional representation rules and Obama’s daunting financial advantage have denied her the elusive knockout. Obama can’t knock her out, but he doesn’t need to. Remember, he’s ahead on points.

Hillary won in Pennsylvania for two key reasons:

1. Pennsylvania only permits Democrats to vote in its primary. Hillary has always won among Democrats. It is among independents, the swing voters in November, that Obama has manifested his greatest strength.

2. Pennsylvania is the second oldest state in the nation after Florida. But while the elderly moved to Florida, Pennsylvania acquired its status by having its young people move out. The result is a demographically atypical electorate.

Both Indiana and North Carolina, the next two states, allow independents to vote in Democratic primaries, and North Carolina has a decidedly young population (it is here that the Pennsylvanian youths moved!). Obama should win both of these states, North Carolina by a lot, Indiana by a little, and their combined effect should wipe out most of the gains Hillary got from her Pennsylvania win.

By the time the voting ends on June 3, Obama will still lead Hillary among elected delegates by 100 to 150 delegates.