She doesn't accept
In the first episode of the BBC comedy Coupling, Steve decides he's going to break up with his partner Jane. He steels up his courage, strides over to her, and makes his pitch. "I'm going to put this very simply. It's over between us," he says. She looks at him quizzically. "You want us to split up?" she asks. "Yes," replies Steve. "Yes I do." She looks at him sweetly. "I don't accept."
Tonight, the Democratic Party essentially told Clinton that it was over. Obama crossed the magic delegate threshold and captured, for all intents and purposes, the nomination. Clinton had run a remarkable race, and come inches from securing the nomination, but she had lost. And tonight, Clinton took the stage in New York, and said, in effect, "I don't accept."
Clinton's speech was a curious spectacle. It's not merely that she didn't concede, but that she didn't even mention that anything had changed. She congratulated Obama on his campaign, but not on his win, or even his likely win. Instead, she continued to talk about her electability, her desire to "count every vote" (every vote, save for a few stragglers in South Dakota, has now been cast and counted), her ability to see Americans whose poverty renders them "invisible" to the other candidates, her faith in the continued efforts of her supporters. It wasn't merely that she didn't concede, but that she didn't stop running, didn't stop attacking.
She admitted that the next few days would require thought as to the path forward, but used that as an opening to plug her web site, where supporters could weigh in on the path she should choose. And on her web site, the button to submit your message of support sits next to an even larger button asking you to contribute. "Throughout this campaign, Hillary has always promised to stand up for you. Show Hillary you're standing with her by making a contribution to our campaign today." If you decide not to contribute, and try to simply leave a message, you're taken to another page where, again, you're asked to contribute. In truth, it is the contribution that Clinton is asking for, not the support. And those donations will not go towards her campaign for the nomination, which cannot be revived by more money. Rather, those donations will go towards retiring her millions in campaign debt. And, in a way, it explain why Hillary refuses to drop out.
So long as she remains in the race, she has leverage. She has purpose. She has supporters who will donate to her efforts. She has reporters who will cover her statements. She has the assurance that the Obama campaign will grow increasingly desperate to facilitate her concession. She has the chance, no matter how slim, that lightning will strike, or scandal will hit, or tragedy will fall, and Obama's campaign will unexpectedly fold in upon itself and she will step forward as the nominee.
It is not so much that she doesn't realize it's over as that she sees no upside in admitting the end. She understands, she just doesn't accept.