The polls indicates a victory, Senate and logically House, for the elections. And President Obama is trying to stem a disaster.
The market would not like a indecisive situation (a reminder of the shameful George W. Bush election). The states of Louisiana (potential run off 6 December) and state of Georgia (potential run off 6 January) are currently too close to call.
A Republican win would be good for healthcare and energy. But would also increase the geopolitical tension as Republican are generally more warmongers (so watch for boots on the ground in Iraq and increased tension with Russia).
Statistically, on a definite election outcome, the market rally in the following weeks.
So all eyes on Louisiana and Georgia tomorrow (unless, as a good Melburnian, you are at the races)