Charlie Cook & Larry Sabato break down the midterm unknowns

<p>It's looking increasingly like we won't be able to call the Senate on Election Day — less than a week from now — as the country braces for results that could contradict what the polling's been showing until then. Larry Sabato, director of the University of Virginia's Center for Politics and the editor-in-chief of the Crystal Ball, and Charlie Cook, founder of the Cook Political Report with Amy Walter, join Chuck to preview where voters' minds might end up on November 8.</p>