Part of the reason that the news media ignore most third-party candidates is that most journalists tend to view campaigns almost exclusively as a contest of winners and losers. The criteria by which journalists judge candidates play to the strengths of the major parties and set up a no-win situation for all other contenders: Third-party candidates are not covered because they do not demonstrate public support, but they cannot gain public support because they are not covered by the news media.
In addition, viewing campaigns mostly as a "contest" is a mistake, because numerous political science studies conducted over the past 50 years strongly suggest that campaigns actually have little impact on election results.
Where campaigns really matter is in their ability to educate the public about new ideas. Studies have shown that while voters don't always remember the specific policy proposals of each candidate when they go to the ballot box, they nevertheless learn enough during the course of a campaign to make sound judgments about which path the country should take.
