He pulled campaign materials from a paper shopping bag, sought advice on which of two hats to wear in front of waiting reporters — before going with the fedora — and had to interrupt a news conference introducing his bid to be New York City’s next mayor.

A cellphone, coming from his trouser pocket, was blaring pop music.

“How many 73-year-old people have the Weeknd on their phone?” said Robert Gangi, a police reform advocate whose nascent mayoral campaign officially began on Wednesday. “We’re obviously a long-shot.”

In a field increasingly crowded with quixotic candidates, Mr. Gangi, a born-and-bred New Yorker from Bensonhurst, Brooklyn, who said he celebrates the city’s bustle and cacophony, faces almost insurmountable odds in trying to wrest the Democratic nomination from the incumbent, Bill de Blasio.