I don't think the Dow is a very good measure of the economy's prospects. It's a good measure of expected corporate profitability and maybe, investor confidence. Neither is doing very well. The Dow is well below 7000 for the first time since 1997.
On election day, 2008, the Dow closed at 9625. Who knows where it will close today, but right now it's at 6814. That's a 29% decrease. Far be it from me to confuse correlation and causality. But if the market continues to fall it will have unpleasant effects on Obama's mood and his policy freedom.
UPDATE: Bryan asks a related question.