“I think I’m in the ballpark now, but it did take me a while,” Mr. de Blasio said, adding: “I think it’s just to the American English ear, the construct is a little counterintuitive. It takes some practice to get the cadence of it right.”

Mr. Sliwa said in an interview that he was trying to do better: “It’ll take time. It’s not intentional.”

Mr. Sliwa, whose last name is pronounced SLEE-WUH, said he understood Mr. Mamdani’s pain.

“Out of 46 years that I’ve been the guy who founded the Guardian Angels, I’d say about 33 years of that time, my name was constantly mispronounced,” he said. “I don’t take offense to it.”

President Trump’s failed efforts to say Mr. Mamdani’s name might be viewed less benevolently, since the president has repeatedly attacked the candidate and threatened to arrest him.

His press secretary, Karoline Leavitt, used an even more outlandish pronunciation, merging parts of his first and last name.

While some pronunciation mistakes might be deliberate, several linguistics experts told The New York Times that both Mr. Mamdani’s first and last name feature letter arrangements and vowel sounds that are not common in English, and it was not a surprise that some people struggled with them.

“Languages differ from one another as to what sequences of sounds are frequent, or even possible to pronounce, and they also differ as to what spellings or letters are associated with what pronunciations,” said Gillian Gallagher, a professor of linguistics at New York University.

There are hundreds more words in English with the sequence “nd” than with “md,” Ms. Gallagher said, adding that these clusters of consonants can lead to speech processes that result in mistakes. One, known as assimilation, involves morphing the second “M” in Mr. Mamdani’s last name into an “N,” making it sound like “Mandani.”

Another, known as substitution, leads speakers to replace the “N” in Mamdani with another “M.”

Those patterns of speech can be difficult to avoid.

“Mamdani has an ‘M’ next to a ‘D’, and that’s hard for English speakers,” said Professor Laurel MacKenzie, a co-director of the NYU Sociolinguistics Lab.

“Our tongues are just not used to making that specific sequence of sounds.”

The softer “Ahn” sound in both Mr. Mamdani’s first and last name can also be challenging. Frequently, “Zohran” has been pronounced with a screeching “Zohr-ANNE.” That miscue is the result of vowels being pronounced differently in Americanized English, said Suzanne van der Feest, an associate research professor at the Graduate Center at the City University of New York.

“That is somebody who speaks mainly English and is just making it into American English vowels,” Ms. van der Feest said.

“It’s an example of how spelling is interfering with how someone’s name is pronounced.”

John Samuelsen, the international president of the Transport Workers Union, said his pronunciation of Mr. Mamdani’s first name feels like a “very common outer-borough way of pronouncing Zohran.” He also noted that he avoids saying Mr. Mamdani’s last name, because “I’m afraid I’m going to mess it up.”

Mr. Mamdani said he once visited a mosque in Manhattan for Friday prayers during the campaign and asked the group to raise their hand if they had ever heard someone consistently mispronounce their name. Most people in the room raised their hands.

“It’s something countless immigrants have experienced,” he said. “When people mock or intentionally distort someone’s name, it’s a way of saying someone doesn’t belong here.”

Mr. Mamdani said he took pride in his name. His mother picked his first name, which means “the first star in the sky.” His father picked his middle name, Kwame, to honor Kwame Nkrumah, the first president of Ghana, who fought for independence.

“Andrew Cuomo never struggles with names like John Catsimatidis,” Mr. Mamdani said in reference to the Greek billionaire grocer. “But somehow Mamdani is too difficult. It’s an issue of prejudice.”

Others have expressed frustration over Mr. Cuomo’s errors, including the journalist Anand Giridharadas, who corrected Mr. Cuomo on MSNBC this week: “This is a very big, diverse city you want to lead. We should get the names right.”

Mr. Cuomo sometimes gets it right.

Rich Azzopardi, a spokesman for Mr. Cuomo, said that the former governor’s name was often botched, too. Indeed, Como, like the Italian lake, is a common mispronunciation for Cuomo, which is pronounced KWO-MO.

“It’s unintentional and he should get over it — people mangle ‘Cuomo’ all the time and you don’t hear us whine about it,” Mr. Azzopardi said.

Ms. MacKenzie and others were quick to note, though, that pronouncing difficult names correctly is not an insurmountable challenge. Practice and a concerted effort to ask people how they pronounce their names helps. That’s particularly the case in New York City, with such a rich array of immigrant communities from across the world.

“We all learned how to say ‘Daenerys Targaryen’ when we were all into ‘Game of Thrones,’” Ms. MacKenzie said.

“We can learn hard names. We can do it. We can figure out how the spellings map to the sounds. We can all get there. We just have to practice.”