It can be mighty hard to remember that there is more on the ballot than the race for president, MUCH more. And what happens at the top of the ticket can have a profound effect on races down the ballot, like races for Congressional seats.
Even so, do not expect the Democrats to win control of the House of Representatives. The districts are drawn to accentuate Republican power in many states, as David Daley told us months ago in his book Ratf**ked.
He adds an addendum to the book with a recent article at Salon. David Daley returns to track Congressional race ups and downs.