http://money.cnn.com/2016/07/30/media/donald-trump-presidential-debates-schedule/

Donald Trump says the fall debate schedule is “unacceptable,” raising the specter that he may try to skip them.
In a tweet on Friday night, Trump incorrectly said that Hillary Clinton and the Democrats are “trying to rig the debates.”
In fact, the fall debate schedule was determined almost a year ago by the nonpartisan Commission on Presidential Debates, a private group made up of both Republicans and Democrats.
His primary complaint is that two of the debates are scheduled on the same nights as NFL games.
That’s true. (It was also true in 2012, and the debates were still high-rated.)
In an interview with ABC News, Trump said he’s “fine” with the commission’s three debates, but objected to the specific dates.
“I’ll tell you what I don’t like. It’s against two NFL games,” he said. “I got a letter from the NFL saying, ‘This is ridiculous.’”
An NFL spokesman said Saturday: “While we’d obviously wish the debate commission could find another night, we did not send a letter to Trump.“