Presidential hopeful Pete Buttigieg, the openly gay mayor of South Bend, Indiana, said in an interview on Sunday that he probably wouldn't be American's first gay president if elected in 2020.

Buttigieg made his comments in an interview with Axios on HBO.

When asked how he responds to critics who say he's “too young, too liberal, too gay to be commander-in-chief,” Buttigieg answered: “I would imagine we've probably had excellent presidents who were gay – we just didn't know which ones.”

“Statistically, it's almost certain,” the 37-year-old Democrat said.

He added that he doesn't know which former presidents were gay.

“My gaydar doesn't even work that well in the present, let alone retroactively. But one can only assume that's the case,” Buttigieg said.

According to Politico, Buttigieg's presidential campaign raised an eye-popping $7 million in April.

One of Buttigieg's donors told the outlet that momentum for fundraising continues to grow.

“It's continuing at a pretty high velocity, [and] the investor's circle is getting wider, more inclusive, and more diverse,” the donor said.

(Related: Pete Buttigieg celebrates first wedding anniversary; says “why not” start family in White House.)