Many commentators have written that the Republicans are more interested in making President Obama look bad and far less interested in solving real problems.
Many Democrats feel that they didn't get the change that they voted for, and as we've seen in New York's Ninth Congressional District, many are inclined not to vote at all.
Many "independents" are dissatisfied with both parties. What happens if a third party candidate appears who has enough appeal to gain wide support among independents? What happens if this candidate manages to get a plurality in some key winner-take-all states? Given our Electoral College system, that third party candidate could gain sufficient electors to "win in a landslide" with way less than half the general election votes.
One always has to be careful what one asks for.