‘The Simpsons’ passed on guest appearance by Donald Trump

The Simpsons staff vetoed the idea of a guest appearance by U.S. President Donald Trump, the long-running show’s executive producer said Saturday.

Appearing on a Simpsons panel at San Diego Comic-Con, Al Jean was asked if the show had ever turned down a celebrity appearance, reports thewrap.com.

After a pause, Jean reportedly answered, “Let’s just say he’s the president of the United States.”

WATCH: Ay Caramba! The Simpsons turn 30

2:05 Ay Caramba! The Simpsons turn 30

There was no immediate answer as to when the request for a Trump appearance was made.

Another executive producer spoke of the now-famous “Bart to the Future” episode from 2000, which alluded to the possibility Trump would be president one day.

READ MORE: ‘The Simpsons’ responds to its prediction of Donald Trump presidency

Matt Selman said the show doesn’t just predict “terrible” events.

The panel was also asked if the show, which airs on the Fox Network in the U.S., has ever been asked to tone down their critique of Fox News.

WATCH: Calgary couple transforms kitchen into Simpsons replica

2:32 Calgary couple transforms kitchen into Simpsons replica

“We started doing Fox News jokes, and they asked us to take it easy on them,” creator Matt Groening replied.

Groening said the request came after the show once called the news channel “not racist, but No. 1 with racists,” according to the Hollywood Reporter.

Groening also managed to get members of the audience to chant “lock him up!” in reference to Trump.

On the 2016 campaign trail, Trump often led crowds at his rallies in the chant, which was directed at his rival. Hillary Clinton.