But if all the splinter third party candidates got their
    act together and mobilized themselves and developed a
    solid platform, they could certainly make a run
    themselves.

Not really. For example, the League of Women Voters used to run the US persidential debate. They've stopped, because the Democrats and Republicans demanded such unfair terms that it would have been a farce. So now the Democrats and Republicans together control the debates.

http://people.howstuffworks.com/debate4.htm