"I don't think it's inconceivable at all that a popular candidate who's caught the popular imagination could exceed 15 percent in the poll standings," he said. "Now more than ever, when you have more non-affiliated voters than ever, that possibility exists."

Newton Minow, a member of the CPD and the former chairman of the Federal Communications Commission, added that the threshold keeps the debates from becoming a free for all.

"There are 410 candidates - let me repeat that - 410 candidates for president registered with the Federal Election Commission," he said. "You want to have 410 candidates in the debate?"

Farah dismisses that argument. He says the rules for access should be that in addition to being Constitutionally eligible and on enough state ballots to win the presidency, a candidate have five percent support or have polls show that a majority of Americans want him or her in the debates.

"You're not going to get hundreds of candidates on the stage if you use these criteria," he said. Under his proposed system, Farah said, Ross Perot would have participated in the debates in 1996 (as well as 1992), and Ralph Nader and Pat Buchanan would have participated in 2000. Only the two major party candidates would have been on the ballot in 2004 and 2008. "It's not exactly a zoo," he said.

Buchanan, who finished in fourth place in the 2000 presidential race and won four states when he ran in the Republican primary in 1992, told CBS News that the system as it now stands amounts to a "monopoly" maintained by the major parties.

"It's an instrument of the two political parties to ensure that the presidency is passed back and forth between them," he said. "The very fact that this duopoly can keep you out of the debates means you don't play in the Super Bowl."

Libertarian candidate Johnson, who is on the ballot in most states and has exceeded five percent in a few polls, argues that his exclusion from the debates is one part of a larger system designed to keep third party candidates marginalized. He and Farah point to "herculean structural barriers" for non-major party candidates, including higher barriers for ballot access and scant press coverage. On October 23, Johnson is participating in the "Free and Equal Debate" with Green Party candidate Jill Stein, Constitution Party candidate and former Congressman Virgil Goode, and Justice Party candidate Rocky Anderson, the former mayor of Salt Lake City.

"Despite the fact that 40 percent of the country is independent and hungry for an alternative, third parties face herculean structural barriers," said Farah. He argues that "because of this fraudulent commission, the candidates can exclude the third party voice and the commission takes the heat."

When it was created for the 1988 campaign cycle, the CPD was undeniably tied to the Republican and Democratic parties. The League of Women voters was once again clashing with the candidates, accusing the George H.W. Bush and Michael Dukakis campaigns of trying to "perpetrate a fraud on the American voter" by agreeing behind closed doors to conditions for the debate (including format and questions) and presenting the document to the League.