Here's a post I did based on a Pollster.com article that those riding the Pollercoaster should ready:
Party ID: The Case for Weights and Historical Margins (Current polls all oversampling Dems)
it is the only poll that is using historical measures of actual turnout for determining it’s Dem to GOP mix.”
Of course, we don’t know if past performance will be the same this time....the D’s sure are investing a lot in their “ground game” and they swear up and down they they have registered millions and will get them out....who knows?