Controversy Over the CPD
Critics charge that the CPD, headed by the former chairs of the Democratic National Committee and the Republican National Committee, is a bipartisan rather than a nonpartisan organization, and can scarcely be expected to be fair to third party and independent candidates.  They also question the CPD's reliance on corporate money and maintain that it lacks transparency.

Clearly some limits must be set as to who will appear on the debate stage, for with too many candidates these events will become unmanageable.  Starting in 2000, the CPD has used three simple criteria.  (In earlier cycles, the CPD used a complicated set of "objective criteria" that drew much criticism).  To participate in the debates, candidates must:

(a) be constitutionally eligible;
(b) have ballot access in enough states to win a majority of electoral votes (at least 270); and
(c) have a level of national support of at least 15 % as measured in polls done by five selected national polling organizations.

In addition to who participates there is the question of content.  Former House Speaker Newt Gingrich has challenged the substantiveness of the CPD-sponsored debates.  In an appearance in Des Moines, Iowa on Aug. 12, 2005 he called for an end to the current tightly formated presidential debates saying they "trivialize the whole process."  Instead, Gingrich said, the candidates should engage in a straightforward dialogue without a moderator for 90 minutes.  During a "Lincoln at Cooper Union" dialogue held on Feb. 28, 2007, Gingrich stated "I propose that we challenge every candidate in both parties to make a commitment before the nominating process begins that if they become the nominee they will agree from Labor Day to the election to nine 90 minute dialogues, one a week for nine weeks..."

Format
The format of a debate has a critical impact on nature of the exchanges that occur and on the amount of information viewers are able to learn. The most obvious parameter to consider is who is on the stage and who is not, but there are many other factors.  Is there a live audience and are they controlled or disruptive?  Is the subject matter confined to one area, such as the economy, or is it more wide-ranging?  What is the time limit on candidate responses and on rebuttals?  Finally, who asks the questions?  The 1960 and 1976-1988 presidential debates exclusively used the panel of reporters.  More recently the single moderator and town hall formats have come into favor.  The town hall format was first used in the Richmond, VA debate in 1992.  Having an audience of undecided voters pose the questions likely results in a broader range of questions, but on the downside this format does not foster follow-up.  One format which has not been attempted is to have the candidates question each other directly.  

Prep
In the lead up to the debates, the candidates undergo intensive preparations.  Briefing books are put together, and the candidates engage in mock debates.  The media provide glimpses of these rehearsals.  The candidates will also be sure to be seen engaging in public displays of confidence such as throwing a baseball, jogging, or giving a thumbs up.

Spin
Following each debate occurs one of the most unique and fascinating scenes in American politics.  Top campaign staff, campaign surrogates and party leaders gather in the media filing center and spin reporters, telling them what they have just seen.  On opposite sides of the filing center chairs are set up for Democratic and for Republican partisans to do satellite interviews with local stations around the country.  Meanwhile, during and after the debate a rapid response unit works feverishly to produce rebuttals to various claims made during the debate; these documents are distributed in the media center and e-mailed out.

Media
In 1988 media were criticized for giving too much attention to the spinners.  Spin soundbites still form an integral part of coverage, but another common element is to assemble a group of undecided voters and interview them for their reactions.  Starting in 1996, the Commission on Presidential Debates has run a Debate Watch program to encourage debate-watching groups around the country.  These groups provide convenient opportunities for local media to do debate coverage.

Third Party Debates
Several third party candidate debates typically occur.  Although C-SPAN does cover some of these, they usually receive virtually no attention.  One organization that has done work on such events is Free & Equal Elections.