Crunching the Numbers: Can Congress change?

CBSNews.com begins a recurring series that takes you behind the scenes with the pollsters and number-crunchers shaping our politics and policy today. In a world that sometimes seems awash in data and statistics and endless arguments, our Elections Director Anthony Salvanto gets them out of the office, away from the computers and formulas -- and tries to make sense of it all.

In this first installment - Can Congress Change? - we chat with targeting guru Mark Gersh, a CBS News consultant, on why midterms, despite unhappiness in the electorate, don't produce a "massive wave" of turnovers - even as Americans' disapproval of Washington hits record highs.

Salvanto and Gersh explore midterm turnout, partisanship and gerrymandering and why the Democrats can't count on the same voters who helped them in 2012.