Clinton also went into Pennsylvania with a big advantage — the demographics matched her strengths and she started with a steep lead in the polls. She won't have that kind of advantage in the coming contests.

Of the states left, the biggest prize is North Carolina, a state that both sides are predicting Obama will win. Clinton dispatched one of her top state organizers, Ace Smith, to North Carolina in an effort to get every vote she can. Smith told reporters last week that getting the percentage spread within single digits would be a victory for Clinton. Obama is also expected to win Oregon and South Dakota.

So where can she look for victory? West Virginia and Kentucky are likely Clinton wins, but they offer fewer than 100 delegates combined. She also has a chance in Guam, Puerto Rico, Montana and Indiana. But none of them is likely to give her a big enough margin to put her over Obama.

To win, she needs to convince voters that Obama is not electable in November even though he's ahead in the delegate race.

She needs a big influx of cash.

She needs a stunning change of fortune.