A 3rd party candidate has an uphill battle. Not so much from lack of exposure, but lack of exposure (i know confusing)
The 3rd party candidate gets the word out only to be stiffled by the media and the Dems & GOP. The 08 election had more than 2 people running, however both D&R did everything possible to have said entities denied stage time during debates. The media (surprise) went along with this farce, thus one more obstacle in the way of a 3rd party. Unless a 3rd party can get a good buzz on the web they will face an up hill battle from D&R and any media circus. After all who wants their apple cart turned over by a legit person from outside the 2 party system.

Another thing is a person running for office spends more time & money discrediting an opponent than actually getting a message out there.
Myself, i feel it's time to vote from the roof top in a manner of speaking.