Accepting or declining debate invitations based on the media company sponsoring the event is a mistake, said Mr. Ailes in a speech at the Radio and Television News Directors Association foundation in Washington.
"Any candidate for high office of either party who believes he can blacklist any news organization is making a terrible mistake about journalism. And any candidate of either party who cannot answer direct, simple, even tough questions from any journalist runs a real risk of losing the voters."
"The public knows if a journalist's question is unfair. They also know if a candidate is impeding freedom of speech and free press. If you are afraid of journalists, how will you face the real dangers in the world?" Mr. Ailes said.
Democratic bloggers and MoveOn.org who believe Fox's news isn't balanced have been pushing the Nevada Democratic Party to drop Fox as host of the August debate and have asked Democratic presidential candidates to skip the debate unless Fox is dropped. Sen. Edwards was the first candidate to drop out.
Miss big audience
On Wednesday night Fox issued a statement saying that it regretted his decision and that Sen. Edwards would miss a big audience.
Mr. Ailes on Thursday went much further.
"There is a long tradition of news organizations, national and local, sometimes together sponsoring presidential and other candidate debates. The organizations and the panelists have been the objects of a lot of advice and even pressure on how these debates should be conducted and what questions should be asked," he said.
"This pressure has been successfully resisted but it is being tried again this year with the added wrinkle that candidates are being asked to boycott debates because certain pressure groups want to approve the sponsoring organization."
Mr. Ailes suggested debate boycotts are a First Amendment issue that both the media and candidates need to fight.
The Edwards campaign did not immediately return a request for comment.