By Lisa Desjardins, CNN

(CNN) – For 25 years, a private non-profit group of roughly a dozen people, operating without oversight, has been running America's presidential and vice-presidential debates.

To some, the Commission on Presidential Debates is a political hero, providing thoughtful stability and ensuring that U.S. presidential candidates do in fact debate each other. Multiple times. In a dignified setting.

But to its critics, the Commission is a small, secretive and closed-minded organization that colludes with the political parties, is out-of-touch with modern voters, and prevents third-party candidates from getting on the debate stage.

Among those critics is George Farah, founder and executive director of Open Debates:

[0:41] "In 1996 Ross Perot was running for president. Three-quarters of the American people wanted to see him and I thought it would be fascinating to see him debating again. And when he was shut out, I was astonished and I thought, who is doing this? What entity is making this happen?"

Since that 1996 disappointment, Farah has become a lightening rod in the presidential debate world.

His organization, Open Debates, relentlessly pushes for changes, like adding more debates, reducing involvement from political parties, a lower bar for candidates to get into the debates, and a broader variety of formats including more candidate interaction and panels of experts asking questions.

This year, his criticism has been particularly sharp on a subject in the headlines, something called the "Memo of Understanding", a secret document negotiated by the political campaigns that lays out debate parameters.

This year's 21-page Memo of Understanding caused a 24-hour firestorm when it was leaked to Time's Mark Halperin prior to last week's town hall debate. It indicated the debate moderator would not be allowed to ask follow-up questions.

But the Commission on Presidential Debates insists that it's not a party to that document and while candidates may agree between themselves to certain rules, like not asking each other questions, the Commission is not governed by that deal.

A source close to planning for the debate last week confirmed to CNN that moderator Candy Crowley never saw the campaigns' Memo of Understanding and that the Commission never asked her to hold back on follow-up questions.

Commission leaders insist they have not signed off on any such memo between the candidates since at least 2000.

That year, the two campaigns involved presented a hefty, 56-page list of demands. Frank Fahrenkopf is co-chairman of the Commission on Presidential Debates:

[3:25] "The [Bush and Gore campaigns] said if you don’t sign this and you don’t get the moderators to sign this, we’ll go elsewhere. And we said, fine, go elsewhere. We’re not signing it."

Editor's Note: Criticisms of the Commission do not end there. Listen to the complete story above for a look at other issues in the presidential debate system and how the Commission on Presidential Debates responds, and then join the conversation below.