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In 1984, the cooperation between the Republican and Democratic parties led to a joint veto of almost 100 proposed panelists for the first debate. The following election cycle saw more of a grab for control by the two major parties. The campaigns of George H.W. Bush and Michael Dukakis met without the knowledge of the League of Women Voters (LWV) and drafted a memorandum of understanding. This secret document specified who would be allowed sit in the audience during the '88 debates and who would serve as panelists, as well as abolished follow-up questions. Under these terms, the LWV would be left to merely host and would have no say in how the debates were held.

In disgust, the League of Women Voters exposed the memorandum and resigned as hosts of presidential debates, citing the "fraud on the American voter" being carried out by the two major parties [source: PBS]. To fill the void left by the LWV, the Democrats and Republicans formed the joint nonprofit bipartisan organization the Commission on Presidential Debates (CPD).

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The fallout from Perot's exclusion from the debates illustrates one of the vital services the CPD provides the two major parties. It acts as a shield. Despite the Democrats and Republicans drafting memorandums of understanding and deciding who can participate, it's the CPD that publicly issues the decisions; so it's the CPD that accepts the public's ire. But since it isn't beholden to the public, the CPD has nothing to lose. In 1996, a poll found that five percent of people polled blamed the Clinton campaign for Perot's exclusion, and Bob Dole's campaign received the blame from 13 percent of respondents. More than 50 percent held the CPD at fault [source: Open Debates].

What's more, the formats of presidential debates under the CPD lent themselves to pat, rehearsed answers that offer little insight into the candidates' views of the issues. In 2000, Sen. John Kerry (who would be the Democratic candidate four years later) criticized the debates: "You could have picked ten people off the street who didn't know Jerusalem from Georgia and they would have had better questions" [source: Open Debates].

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