2020 presidential candidate Pete Buttigieg could make history as the youngest president in the history of the United States — and the first openly gay one. Buttigieg, however, believes he wouldn't be the only gay president.

Pete Buttigieg Axios on HBO

Buttigieg, the 37-year-old mayor of South Bend, Indiana, came out as gay in 2015, before being elected to his second term as mayor. He is now married to junior high school teacher Chasten Glezman, who would become first gentleman if Buttigieg wins the presidency.

In an interview with "Axios on HBO," Buttigieg was asked about critics potentially saying he's too young, too liberal and too gay to be commander-in-chief.

He was asked, "You are young. You are a liberal. You are gay. How will you respond?"

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"I'll respond by explaining where I want to lead this country," the candidate replied. "People will elect the person who will make the best president. And we have had excellent presidents who have been young. We have had excellent presidents who have been liberal. I would imagine we've probably had excellent presidents who were gay — we just didn't know which ones."

Buttigieg said "statistically, it's almost certain" that there has been a gay president before. Of course, none have been openly gay, and almost every president, except for two, have been married to women.

An estimated 4.5 percent of the U.S. population is LGBTQ, a 2018 study by the Williams Institute at UCLA School of Law found. So Buttigieg's assumption that at least one out of the nation's 45 presidents was gay is not so far-fetched — he just doesn't know which one.

"My gaydar even doesn't work that well in the present, let alone retroactively," he told Axios. "But one can only assume that's the case."