One thing that does seem very clear tonight -- at least if what I'm hearing from the exits is true -- is that the much-ballyhooed youth vote simply did not show up. Simple as that.

That is a remarkable turnabout from the expectations that had been growing over the last week. And Democrats weren't the only ones who bought into the idea. Public pollsters and even Republicans in the final days of the campaign were coming to believe it too. And that shaped expectations greatly.

Whatever happens tonight a lot of thought and study will go into just what happened. Was it a mirage? Was it a problem with the GOTV operation? It can't simply be the later. Even the best ground operation can only amplify a demographic trend or spike that has some deeper socio-political basis.