A last-minute surge, cross-endorsements to game ranked-choice voting, and 100-degree heat on Election Day could put a socialist in Gracie Mansion.

A new poll released Monday by Emerson College shows a Democratic Socialist state assemblyman, Zohran Mamdani, beating Governor Cuomo in the eighth round of ranked-choice voting with 51.8 percent of the vote to Mr. Cuomo’s 48.2 percent. This is the first major nonpartisan poll to show Mr. Mamdani winning the Democratic mayoral primary.

Early voting started more than a week ago. Election Day is Tuesday.

Temperatures in the city are expected to reach 99 degrees on Tuesday with a “real feel” of 106 degrees, according to AccuWeather. The scorching heat could prevent older New Yorkers — who favor Mr. Cuomo and tend to vote on Election Day — from voting.

More than 380,000 New York Democrats have already cast their ballots, according to the Board of Elections. The overwhelming majority of these votes come from Brooklyn and Manhattan, by a margin of more than 2-to-1 over the other boroughs combined.

Mr. Mamdani holds a 10-point lead among voters who have already cast their ballots, according to the Emerson poll. His base of support is white and Asian, less than 50 years of age, college-educated, and live at Brooklyn or Manhattan. 

To put these numbers in perspective, only 800,000 New Yorkers voted in the 2021 Democratic mayoral primary. This means either nearly half the electorate has voted early this year or there is a surge of new voters. Mr. Mamdani is promising free buses, a rent freeze on stabilized apartments, and “a network of city-owned grocery stores.” 

“Over five months, Mamdani’s support has surged from 1 percent to 32 percent, while Cuomo finishes near where he began,” the executive director of Emerson College Polling, Spencer Kimball, said. “In the ranked-choice simulation, Mamdani gains 18 points compared to Cuomo’s 12, putting him ahead in the final round for the first time in an Emerson poll.”

Since 2021, New York City has been using a ranked-choice voting system in its municipal primaries. Voters can list up to five candidates on their ballots in order of preference. The candidate with the lowest number of first-choice votes gets knocked out in round one, with the second choice on those ballots earning that person’s vote. This repeats in subsequent rounds until a candidate breaks 50 percent to win.

Among the 11 candidates on the ballot, Mr. Cuomo earns the most support in the first round of voting and is still slightly ahead of Mr. Mamdani through the seventh round, according to the Emerson poll. When the third-place candidate, Brad Lander, the city comptroller, gets knocked out after the seventh round, though, a majority of his 20 percent of the vote goes to Mr. Mamdani. This sends the Democratic Socialist over the 50 percent threshold.

Messrs. Lander and Mamdani cross-endorsed each other last week, encouraging their supporters to rank the other as their second choice. The progressives in the race are telling voters not to rank Mr. Cuomo. The former Empire State governor’s only cross-endorsement comes from a businessman, Whitney Tilson, who is polling at 1 percent.

“Voting is ritualistic and habitual,” a Democratic strategist, Hank Sheinkopf, tells The New York Sun. He says ranked-choice voting favors candidates who appeal to college-educated voters. “All reform has an upper-class bias,” he says.

Mr. Cuomo does best in the Bronx and Queens/Staten Island, according to a Marist poll released last week that shows the former governor winning. Mr. Cuomo’s base is moderates, Blacks, New Yorkers over age 50, working-class voters in the boroughs other than Manhattan, and those without college degrees.

The Emerson poll shows Mr. Cuomo beating Mr. Mamdani by a 24-point margin with Blacks, by a 26-point margin among voters in their 50s, and by a 12-point margin with those over 60 years of age. He needs these voters to come out in large numbers.

“Together we will win. Together we will restore effective leadership to City Hall. But only if each of us shows up and votes,” Mr. Cuomo said in a post to X Monday.  
“We have gone from the margin of error to the margin of effort,” Mr. Mamdani said in a post to X alongside the Emerson poll. “On the day before the election, we stand on the verge of toppling a political dynasty and winning a city we can afford.”