Mamdani debuted the mustache while handing out water to runners at the New York City Marathon on Sunday, CNN reports. He shaved his beard and left a thick row of black hair above his lip.

The look was so new that many runners raced past without knowing him, CNN says.

In a video posted to social media on Monday evening, the mayor said the mustache was in honor of Movember, CNN reports. The yearly event backs men's health causes such as prostate and testicular cancer.

Twirling the ends of the mustache, Mamdani said he was not just paying “lip service” to the issue, CNN says. He pointed to a $4 million investment in a new prostate cancer center at a hospital in Brooklyn.

The new look made quick headlines, CNN reports. New York magazine's The Cut called him “Mayor Mustache,” the network says, and others online debated whether he was more of a beard guy.

Mamdani's slim suits and trimmed beard had become a signature look, CNN says. Some men even copied the look as Halloween costumes this year.

Mustaches are still fairly rare among American politicians, who tend to be clean-shaven or bearded, CNN notes. The Movember campaign began in Australia in 2003.

The campaign lets men try a mustache for a month before deciding whether to keep it in December, CNN says. “Handlebar next?” the mayor asked Council Member Rita C. Joseph in the video.

Only CNN has reported this so far, and NewsHabit hasn't seen independent confirmation.

What we know: Mamdani said in a video that his new mustache is for Movember.
What we don't: Whether he will keep it after the month ends. No second outlet has confirmed the details yet.