I'm going to try to sum this up nice and sweet zenmaster. CPD is the Commission on Presidential Debates. They took over the debates - after being jointly formed by the two parties - in 1988 because the League of Women Voters (who used to run the debates) wouldn't bow to the demands of the two major parties. They had invited a third party candidate a couple times - one publicized time one of the major party candidates (I think it was Carter?) flat out REFUSED to debate the third party candidate. The CPD was jointly created by the two parties to run the debates, thus giving the two parties control over how they are run and the ability to lock out third parties. Ross Perot broke through the barrier they set and made it into the debates in 1992 (I believe the limit at the time was 5% in a certain number of national polls) and it was devastating to the election. It turned everything upside-down (Ross Perot got a whopping 18% of the popular vote - something I attribute almost entirely to the fact he was allowed into the debates and support for why I think it's so extremely popular to get 3rd parties into the debates).So, before the 1996 election, the CPD changed the rules and made it 15% required in sepereate polls. Well, if you're a fledgling party it's pretty difficult to get 15% of seperate national polls without being given a forum to express your views.
For more information about the sad status of debates in this country, see
http://www.opendebates.org
http://www.pbs.org/now/transcript/tr...pt_debate.html
http://www.citizensdebate.org/