A curious thing happened last weekend when Representative Lee Zeldin brought his Republican campaign for governor of New York into Hasidic Brooklyn.

Mr. Zeldin, a pronounced underdog, was greeted like a rock star. Crowds chanted in approval. Yiddish-language campaign posters littered the streets. “Mister Lee Zeldin, you got my vote,” a paramedic yelled out of an ambulance inscribed in Hebrew lettering.

Mr. Zeldin, one of only two Jewish Republicans in Congress, has long been a fierce supporter of Israel and a fixture at Republican Jewish Coalition events. But in recent weeks, he has maneuvered aggressively to position himself in lock step with Orthodox Jewish concerns over an increase in hate crimes and ongoing state attempts to regulate private religious schools, known as yeshivas.

“It’s not just on our streets, but even in our schools where we are being targeted,” he said during a visit Sunday to Borough Park.

With less than 50 days until Election Day, Mr. Zeldin’s Jewish outreach is at the center of a concerted and overlooked effort to court enclaves like these in boroughs outside Manhattan, where English is often a second language and voters appear to be highly motivated by education issues, congestion pricing and threats to public safety — along with a leftward drift among Democrats they have long supported.

Mr. Zeldin, whose campaign is strongest in areas far outside New York City, has recently made other stops in the city at Asian American neighborhoods in Sunset Park, Brooklyn, and Flushing, Queens; Russian-speaking communities around Brighton Beach, Brooklyn; and a conservative Hispanic church in the Bronx. Pro-Zeldin super PACs are providing backup with foreign-language ads and outreach on WeChat and WhatsApp.

Whether he can move enough votes to destabilize Democrats’ New York City firewall remains to be seen. Recent polls from Emerson and Siena Colleges show him trailing Gov. Kathy Hochul, a Democrat, by roughly 15 percentage points, although other polls suggest that the race may be tighter.

No Republican candidate for governor has earned more than 30 percent of the city vote — Mr. Zeldin’s benchmark — in two decades. And even if he did, he would still have to pull off commanding victories upstate and in New York’s increasingly diverse suburbs to beat Ms. Hochul, who is spending freely from overflowing campaign accounts to try to ensure that does not happen.

But for New York Republicans locked in the political wilderness since former President Donald J. Trump’s election, the promise of a longer-term realignment among crucial Asian and Jewish voting blocks is tantalizing — even if the party has to wait until after November for it to happen.

“These are voters who are free agents,” said Chapin Fay, a former Zeldin adviser leading one of the super PACs, who nonetheless remains worried Republicans are not doing enough to capitalize on the opening.

The recent Emerson College poll found Ms. Hochul leading among voters who identified as Asian, but by only 10 percentage points, compared to her 37-point lead among Hispanics and 60-point lead among African Americans.

“It’s hard for me to go into any group that I’m in without seeing a Zeldin news article, or a flier, or a Republican piece of literature, on WeChat,” said Yiatin Chu, the president of Asian Wave Alliance, a nonpartisan political club formed to help organize voters.

Ms. Chu has never voted for a Republican. But after Mr. Zeldin met with a group of Asian leaders last year, she was convinced that he would prioritize fighting anti-Asian violence, and block changes to the admissions process for elite public schools, which enroll large numbers of Asian Americans.

“My message to Democrats locally and nationally is please don’t take our communities for granted,” said Representative Grace Meng, the state’s only Asian American congresswoman, who started sounding alarms about aggressive Republican outreach in her Queens district last year.

But she predicted that Ms. Hochul would fare well there, particularly given her outspoken support for abortion rights, aggressive steps to combat gun violence and distance from former Mayor Bill de Blasio’s unpopular education policies.

As for Mr. Zeldin’s outreach: “It’s a little late.”

Democrats are making their own large investments in many of the same communities, along with more reliable segments of the party’s base that could offset Mr. Zeldin’s gains.

Ms. Hochul’s campaign said it would spend six figures on ads aimed at Jewish voters and another $1 million on Spanish-language ads. Many will tout her work on gun control and mental health while hammering Mr. Zeldin for opposing abortion rights and supporting Mr. Trump, who remains broadly unpopular here.

Despite Mr. Zeldin’s optimism about Orthodox Jewish groups, some estimates suggest that the Hasidic vote typically represents less than 2 percent of statewide turnout, while other religious Jewish groups, including the modern Orthodox, account for another 2 to 3 percent. And Ms. Hochul, who made a series of cold calls last week seeking to shore up ties with prominent Jewish allies, is still expected to win Jewish voters overall, running up the score among non-Orthodox voters.

“From Borough Park to the South Bronx, Governor Hochul has built a broad coalition of New Yorkers who are supporting her campaign because of her effective leadership and ability to get things done,” said a Hochul spokesman, Jerrel Harvey.

Still, Mr. Zeldin may have good reason to think he can notch gains.

In southern Brooklyn, Russian and Ukrainian immigrants — many of them Jewish — helped flip a City Council seat for Republicans last year. The large population of immigrants who fled the former Soviet Union voted enthusiastically for Mr. Trump and have increasingly rejected Democrats — even moderates like Mayor Eric Adams and Ms. Hochul — for their ties to a party that harbors a small minority of democratic socialists.

“Even if it’s a centrist Democrat, they will select a Republican at this point,” said Inna Vernikov, a Democrat-turned-Republican who won the Council seat.

Republicans also believe opposition to the state’s new congestion pricing plan, which would make commuting into Manhattan more expensive for middle-class New Yorkers at a time of sharp inflation, could help motivate turnout.

For now, the competition for votes appears to be fiercest in New York’s politically influential and fast-growing Hasidic communities, which have also shifted quickly to the right in recent years.

Though they are not exceptionally large, these groups tend to turn out when other voters do not and vote as a bloc. And right now, they may be some of the most motivated voters in the state.

Hasidic Jews have been particularly visible targets of an uptick in antisemitic violence. And in recent weeks, government intervention in Hasidic yeshivas has been framed as an existential threat to the community.

Earlier this month, The New York Times published an investigation that found that roughly 100 Hasidic boys’ schools were systematically denying their students a basic secular education and regularly using corporal punishment, while receiving large sums of taxpayer funds. A few days later, a state education panel passed long-awaited rules to regulate nonreligious studies in private schools.

“New York State declares a war against its ultra-Orthodox residents,” screamed the front page of Der Blatt, a Yiddish-language newspaper.

While Ms. Hochul has maintained a studied silence on yeshivas, Mr. Zeldin had sought to capitalize on the issue.

In recent days, he has crisscrossed Hasidic areas to declare that he will protect yeshivas from the government he is hoping to run. Mr. Zeldin often stresses that his mother taught at a yeshiva, and highlights his defense of Israel in Congress. (Mr. Zeldin is also targeting modern Orthodox Jewish voters, who often vote for Republicans.)

English- and Yiddish-language ads quickly appeared last week to amplify Mr. Zeldin’s defense of the yeshivas. “They both want our support,” one read, referring to the two candidates. “Only Lee Zeldin stands up to defend us. Only Lee Zeldin is a friend we can rely on.”

Earlier this summer, Mr. Zeldin visited a summer camp in the Catskills with Joel Rosenfeld, a Hasidic leader. Sitting in front of a hand-scribbled sign that read “Make New York Great Again,” Mr. Zeldin listened as a large group of boys sang in unison.

“A governor who hears, a governor who cares, that’s Congressman Lee Zeldin,” they sang, raising their voices for the finale: “A leader who understands our needs and demands, Congressman Lee Zeldin!”

Mr. Zeldin began his day Sunday with a visit to the grave of Rabbi Menachem Mendel Schneerson, the revered leader of the Lubavitcher group of Hasidic Jews.

Later in Williamsburg, he visited the book-lined apartment of a religious leader of a minor Hasidic sect, where he cited statistics about antisemitic violence and suggested the state should be more concerned about struggling public schools than yeshivas.

All of it has fueled speculation about whether he will win endorsements from Hasidic groups that backed Ms. Hochul in the primary.

Yet Hasidic leaders have maintained an intensely pragmatic streak in local elections, supporting ruling Democrats and calling upon their followers to do the same. Supporting a Republican could be risky for Hasidic leaders who rely on Democrats to serve a community that has some of the highest poverty rates in New York — and who draw some of their power from a perception among politicians that their word moves votes.

Still, some religious leaders may decide to back Mr. Zeldin, or simply stay neutral, with the knowledge that many Hasidic voters are likely to support the congressman, regardless of how their leaders steer them.

Moishe Indig, a Hasidic leader whose group has not yet made an endorsement in the race, said in a statement: “Governor Hochul has always been a friend of our community and she remains a friend of our community.”