The fight for the Democratic presidential nomination will begin to assume a more concrete shape on the nights of June 26 and 27, when twenty candidates take the stage in Miami for the first round of debates. They qualified to participate by meeting one of two criteria before June 12: securing a minimum number of donors (at least 65,000) or registering more than one percent support in three major polls. The qualifying criteria are the same for the second round of debates in Detroit on July 30 and 31. For the third round, to be held on September 12 and 13 (in a location not yet chosen), the criteria are essentially doubled, which could winnow the field considerably. The Democratic National Committee has sanctioned twelve debates, to be held until next April.
Source : The Rules of the Game
