That's the assumption behind disappointment at the 2008 turnout final results and results in Bloomberg sentences like this:
Still, turnout fell short of the 140 million voters many experts had forecast.
Mark Blumenthal tries to find any evidence that those experts existed.
This article available online at:
http://www.theatlantic.com/daily-dish/archive/2008/12/who-expected-140-million-votes/207881/
