Spencer Platt via Getty Images In this file photo from February, GOP presidential candidate Donald Trump speaks with CNN's Anderson Cooper. Trump has complained that Cooper shouldn't be allowed to moderate a presidential debate because of how he "behaves."

Donald Trump has promised to take part in all three scheduled debates, but he’s already complaining about at least one of the moderators.

In a Washington Post interview published Thursday evening, Trump described CNN’s Anderson Cooper as “very biased” and said he shouldn’t be allowed to moderate a debate.

“I don’t think Anderson Cooper should be a moderator because Anderson Cooper works for CNN and over the last couple of days, I’ve seen how Anderson Cooper behaves,” Trump said.

Despite his unhappiness with the moderator situation, the Republican presidential candidate still plans to attend the debate.

“He’ll be very biased, very biased. I don’t think he should be a moderator. I’ll participate, but I don’t think he should be a moderator. CNN is the Clinton News Network and Anderson Cooper, I don’t think he can be fair.”

Cooper will co-moderate the second debate, scheduled for Oct. 9, with ABC’s Martha Raddatz.

If history is any indication, Cooper is likely to be tough on both candidates.

At one point, he confronted Clinton on her history of changing positions on key issues, asking: “Will you say anything to get elected?”

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.