Sam Wang, bucking the conventional wisdom, claims that the "transfer of control is more likely than not." Money quote:
Using all polls and median-based statistics to address issues of outlier data gives the median of D+4.0% that I gave. That translates to a narrow 16-seat Democratic majority in an election held today.
This would be an unusual outcome. It would involve a Democratic net pickup of over 30 seats, much more than the typical gain for a re-elected president’s party. But 2010 was also an exceptional wave year for the Republicans. Again, think of the pendulum. In any event, this is what the numbers are currently telling us.