Who the next mayor of New York City is will all come down to turnout — first in the Democratic primary this Tuesday and then in the general election in November.

This may seem like an obvious statement, but for an off-year mayoral election — which has historically low turnout — with a surging candidate who appeals to low-propensity young voters, turnout will be the deciding factor, according to politicos who spoke with The New York Sun.

The Democratic primary has become a two-person race between a former New York State governor, Andrew Cuomo, and a Democratic Socialist state assemblyman, Zohran Mamdani. The city comptroller, Brad Lander, who on Tuesday was arrested and later released  by Immigration and Customs Enforcement officers, comes in a distant third in most polls. 

Mr. Mamdani needs young people to vote in unprecedented numbers for him to win. His base is mainly white and Asian, college educated, and lives in Brooklyn or Manhattan. Mr. Cuomo is banking on a traditional coalition of Blacks, the working class, orthodox Jews, and moderates to vote for him. He spent Saturday making his closing arguments with the Reverend Al Sharpton at the National Action Network headquarters in Harlem. He visited several Black churches on Sunday.

Since early voting started on Saturday, more than 90,000 registered Democrats have cast their ballots — double the number in the first three days of early voting in 2021. Brooklyn and Manhattan have seen the largest numbers of early voters, according to the Board of Elections. Roughly 800,000 registered Democrats voted in the 2021 primary. Just more than 1 million New Yorkers voted in the general election, a small number for a city of more than 8 million people. 

“It’s a turnout election,” a Democratic strategist, Hank Sheinkopf, tells the Sun. Of early voters, he says they are “likely to be Mamdani voters that they’ve organized, which are turning out in numbers that people haven’t seen in a while.”

A Muslim American former rapper with a spotty work history and the worst attendance in the state assembly, Mr. Mamdani has used social media to coalesce what is undoubtedly the most enthusiastic base of supporters and volunteers in the race. He addressed a packed Terminal 5 concert venue on Saturday night with a progressive superstar congresswoman, Alexandria Ocasio Cortez.

The event looked more like a concert than a political rally. The Democratic Socialists of America were there to sign up volunteers and get out the vote. Outside a Mamdani debate watch party held last week by the Democratic Socialists of America, the Sun overheard a supporter who looked to be about 30 years old tell a friend Mr. Mamdani is remaking the Democratic Party.

Senator Sanders — of an older generation but a godfather to this “new” progressive and socialist wing — endorsed Mr. Mamdani on Tuesday morning. “At this dangerous moment in history, status quo politics isn’t good enough. We need new leadership that is prepared to stand up to powerful corporate interests & fight for the working class,” Mr. Sanders posted to X.

Mr. Mamdani is fashioning himself as a defender of the working class, with his promises of free buses, free childcare, and a rent freeze on stabilized apartments. Yet he is the son of a successful movie director and Columbia University professor who went to a $90,000-per-year mid-tier liberal arts college — and Mr. Cuomo is the candidate with a working-class base and the most union endorsements.

Perception, though, may matter more in politics than reality. The Terminal 5 event Saturday was reminiscent of President Trump’s rallies in 2016, when pundits said attendees with their red hats loved the show but wouldn’t vote in large numbers. We all know how that ended.

Most polls show Mr. Cuomo winning. A Manhattan Institute poll released Tuesday shows Mr. Cuomo earning 43 percent of the vote in the first round to Mr. Mamdani’s 30 percent. Mr. Cuomo prevails in the poll in the 10th round of ranked-choice voting with 56 percent to Mr. Mamdani’s 44 percent.

Another poll released Tuesday by the Center for Strategic Politics, commissioned by the progressive anti-Cuomo PAC DREAM — “Don’t Rank Evil Andrew for Mayor” — shows a virtual tie between Messrs. Cuomo and Mamdani in the final round of ranked-choice voting. Mr. Cuomo is 8 points ahead in the first round, but the final round shows Mr. Cuomo with 52 percent to Mr. Mamdani’s 48 percent, within the poll’s margin of error.

“Cuomo still wins it as of now,” a political strategist who works on both sides of the aisle, E. O’Brien Murray, tells the Sun. “Even the progressive polling, as much as they try to push it, doesn’t show a path to victory yet for Mamdani. It becomes a turnout race, but everything still shows Cuomo in the lead.”

Mr. Sheinkopf says he’s wary of polls, saying they target high-propensity voters, which Mr. Mamdani’s adoring fans are not. He also says that ranked-choice voting favors educated voters who understand the strategy of who to include and not include in the ranking. Mr. Mamdani’s top position on the physical ballot could also help him.

“Voting is ritualistic and habitual,” Mr. Sheinkopf says. On ranked-choice voting, he says, “All reform has an upper-class bias.”

The progressive candidates are using ranked-choice voting to their advantage. Messrs. Mamdani and Lander cross-endorsed this week, telling their voters to rank the other second. Mr. Mamdani also cross-endorsed with a candidate earning 1 percent of the vote in most polls, Michael Blake. Were it not for ranked-choice voting and matching funds, Mr. Murray says many of the low-polling candidates would have already dropped out of the race.

Mr. Cuomo may not inspire a movement like his 33-year-old self-described socialist competitor, but he is trying to hit Mr. Mamdani hard on his lack of experience. He attacked him at the last debate for getting only three bills passed during his time in the assembly. “I think inexperience is dangerous,” Mr. Cuomo said. “And now you have Donald Trump on top of all of that.”

Mr. Cuomo got an assist in this from the New York Times editorial board on Monday. “We do not believe that Mr. Mamdani deserves a spot on New Yorkers’ ballots. His experience is too thin, and his agenda reads like a turbocharged version of Mr. de Blasio’s dismaying mayoralty,” the Times wrote.

“As for Mr. Cuomo, we have serious objections to his ethics and conduct, even if he would be better for New York’s future than Mr. Mamdani. For any voters tempted to leave both off their ballots, it is important to understand that this decision would be tantamount to expressing no preference between the two.”

In New York mayoral elections, the Democratic primary usually decides the race — but this year could be different. If Mr. Cuomo wins the Democratic primary, the Working Families Party would likely run Mr. Mamdani on its line. If Mr. Mamdani wins the Democratic primary, Mr. Cuomo could run on an independent line he set up.

Mayor Adams is running for re-election on two independent lines. The Guardian Angels founder, Curtis Sliwa, is running as a Republican. A former United States attorney, Jim Walden, is running as an independent.

The Manhattan Institute poll shows Mr. Cuomo winning in the general if he clinches the Democratic nomination, regardless of whether Mr. Mamdani runs on the Working Families Party line. If Mr. Mamdani wins the primary and Mr. Cuomo bows out, where do the former governor’s voters go? The poll shows Mr. Mamdani winning in November as a Democrat, but nearly 30 percent of voters are undecided, and Mr. Adams trails by only 14 points.