You have to admire Hillary's determination. Being the underdog brings out the best in her--and it either neutralizes or makes forgivable the less appealing aspects of her campaign and character.
She remains the underdog. Her victory in Pennsylvania was solid without being startling. The margin was exactly what was required to make it certain that she would stay in the race--yet without much altering the arithmetic that so strongly favors Obama. Her ten-point advantage is less than she needed to get on track to overturn Obama's lead in the Democratic popular vote (although, admittedly, this depends on how you measure it); his lead in pledged delegates was secure in any case. It is not enough, either, to persuade wavering superdelegates that the Obama campaign is failing--or at any rate, failing so badly that they could override a pledged-delegate lead without tearing the party to pieces. Having said all that, once again she arrested his momentum, and raised questions about his ability to close the deal.
He can argue that he came through the Wright and Bittergate affairs unscathed. His overall result in Pennsylvania was close to his performance in Ohio, a demographically similar state, which voted before those recent setbacks. Indeed, he made big inroads on Hillary's early lead. One wonders whether, if not for Bittergate, he would have held her to a closer result, and maybe even won--in which case it would all have been over. But he did not, and, money permitting, this result most likely gives Hillary enough momentum to keep going through all the remaining primaries.
What kind of campaign will she fight from now on? As I say, she will most likely end up losing, but what matters for the party's electoral prospects in November is the manner of her losing. She may increase the intensity of her attacks on Obama--which puts her party as well as her own reputation at risk. Or perhaps she will strike a more positive note, calculating that a negative assault does not meaningfully improve her chances. You could argue that her best hope now is to stay viable as a candidate and pray that Obama makes some terrible error, and she does not need to go negative to do that. It will be interesting to see whether Hillary is capable of that kind of tactical compromise--whether she can do anything but fight all out, whatever it takes.