Andrew Cuomo is campaigning in the Bronx on Tuesday as he tries to get out the vote in a borough he won in the Democratic primary but that is comparatively lagging in early voting.

Mr. Cuomo has three events scheduled for Tuesday in the Bronx, two of them with seniors. Super PACs working to elect Mr. Cuomo are also moving resources and paid canvassers to the borough to get out the vote.

This focus on the Bronx comes as early voting numbers are surging across the city, particularly with voters over the age of 50 — a positive sign for Mr. Cuomo. A Suffolk poll released on Monday shows Mr. Cuomo is closing the gap on the Democratic nominee, Zohran Mamdani, though the former governor is still behind by 10 points.

If Mr. Cuomo is going to eke out a long-shot win in this election, he needs to rally his base of support to come out to the polls. He won the Bronx by 18 points in the first round of ranked choice voting in June’s primary. The only other borough Mr. Cuomo won in June was Staten Island, whose vote is likely to split between Mr. Cuomo and the Republican nominee, Curtis Sliwa.

Early voting numbers are strong in the Bronx but not as compared to the surges in Manhattan, Brooklyn, and Queens — boroughs that helped the 34-year-old state assemblyman and self-declared socialist, Mr. Mamdani, win in June.

Three times as many Bronx residents — 19,096 to be exact — have cast ballots in the first three days of early voting as did in the same three days of the last mayoral election in 2021. For comparison, five times as many voters have cast ballots in Manhattan and Brooklyn and six times as many in Queens as did four years ago. Staten Island has a third of the population of the Bronx — and less than half as many registered voters — but nearly the same number of early votes cast so far in this election.

“I don’t think there are many undecideds. I think it’s about how motivated people are to vote,” Mr. Cuomo told the Sun’s Editorial Board last week.

The Cuomo campaign does seem to be ratcheting up its turnout game. Mr. Cuomo held a Young Professionals for Cuomo event on Tuesday night. He posted a commitment to saving the Elizabeth Street Garden at Nolita, which will likely mobilize some downtown residents to vote for him. Mr. Mamdani wants to tear down the garden for affordable housing.

The strong early voting numbers in Manhattan were concentrated on the Upper East and Upper West Sides over the weekend. The Upper West Side split between Messrs. Cuomo and Mamdani in the primary, but the Upper East Side is more of a Cuomo stronghold.

“They will not be voting for Mamdani,” a Democratic strategist, Hank Sheinkopf, says of the Upper East Side. “The Bronx — if they’re cooperative apartment owners voting — they’re not stupid, they’re not going to vote for Mamdani.”

Roughly 1.1 million New Yorkers voted in the 2021 mayoral election. Some strategists say turnout needs to hit at least 1.4 million — probably higher — for Mr. Cuomo to win, estimating that Mr. Mamdani’s base of support is about 600,000. Mr. Mamdani earned 573,000 votes in the primary.

The Mamdani campaign appears worried about the early voting numbers, though the candidate says he’s not. The campaign, with the help of the Democratic Socialists of America, did effectively mobilize its young, infrequent, or first-time voters out to the polls in the primary, trouncing Mr. Cuomo.

“The highest number of early voters so far are in age brackets where Cuomo either ties or leads Zohran in the latest polls,” a Mamdani campaign email message to supporters on Tuesday said.