By STEVE PEOPLES and ANTHONY IZAGUIRRE

NEW YORK (AP) — The stunning success of Zohran Mamdani, a 33-year-old self-described democratic socialist, in the race for New York City mayor has exposed anew the fiery divisions plaguing the Democratic Party as it struggles to repair its brand nearly half a year into Donald Trump’s presidency.

A fresh round of infighting erupted among Democratic officials, donors and political operatives on Wednesday, a day after Mamdani’s leading opponent, former New York Gov. Andrew Cuomo, conceded the Democratic primary. Mamdani appears on a glide path to the nomination, though ranked choice vote counting will determine the final outcome next week.

Many progressives cheered the emergence of the young and charismatic Mamdani, whose candidacy caught on with viral campaign videos and a focus on the cost of living. But the party’s more pragmatic wing cast the outcome as a serious setback in their quest to broaden Democrats’ appeal and move past the more controversial policies that alienated would-be voters in recent elections.

Indeed, Wednesday’s debate was about much more than who would lead America’s largest city for the next four years.

Giddy Republicans viewed Mamdani’s success as a political gift that would help shape elections across New Jersey and Virginia this fall and into next year’s midterms. And while such predictions are premature, national conservative media focused on the New York election with fresh zeal, suggesting that Mamdani’s emerging profile as a prominent Democratic leader will surely grow.

Trump took aim at Mamdani on social media, calling him “a 100% Communist Lunatic.”

“We’ve had Radical Lefties before, but this is getting a little ridiculous,” the president wrote. “Yes, this is a big moment in the History of our Country.”

Some Democrats think so, too.

Lawrence Summers, the Treasury Secretary under former Democratic President Barack Obama, aired dire concerns on social media.

“I am profoundly alarmed about the future of the (Democratic Party) and the country” because of the New York City results, Summers wrote.

Vermont Sen. Bernie Sanders, who had endorsed Mamdani, scoffed at such Democratic critics and instead called for them to follow Mamdani’s lead.

“In many ways, Mamdani’s campaign really shows the direction in which the Democratic Party should be moving. And that is not to worry about what billionaires want, but to worry about what working-class people want,” Sanders told The Associated Press.

The Vermont senator warned Republicans against premature celebration.

“People like Mamdani are their worst nightmares,” Sanders said of the GOP. “It’s one thing for the Democrats to be strongly against Donald Trump. It is another thing to give working class people something to vote for — a positive agenda.”

Assuming Mamdani ultimately is the Democratic nominee, he would move to a November election against embattled Mayor Eric Adams, who is running as an independent, Republican candidate Curtis Sliwa and maybe even Cuomo again, should he also choose to run as an independent.

A member of the New York state Legislature since 2021, Mamdani won over Democratic primary voters with an optimistic message centered on the cost-of-living backed by a sprawling grassroots campaign that brought out thousands of volunteers across the city’s five boroughs. Initial precinct data shows that he did well in the city’s wealthier enclaves while Cuomo struggled in all but majority Black and orthodox Jewish neighborhoods, along with the more conservative Staten Island.

Mamdani’s rise was aided by Cuomo’s baggage. The 67-year-old Democrat was trying to mount a political comeback from a sexual harassment scandal that forced him to resign the governorship in 2021.

Mamdani has had to sidestep a field of landmines of his own making, centered on his policies and political rhetoric.

He called the New York Police Department “racist, anti-queer and a major threat to public safety” in a 2020 social media post. As a mayoral candidate, he softened his stance and said that the police served a vital role. Still, he pushed for the creation of a new public safety department that would rely more on mental health care services and outreach workers.

On Israel’s war in Gaza, he used the term “genocide” to describe Israel’s actions in the conflict. In the primary’s closing stretch, Mamdani also defended the phrase “ globalize the intifada,” which he described as “a desperate desire for equality and equal rights in standing up for Palestinian human rights.”

He also faced criticism over his identity as a democratic socialist, a label he refused to back away from.

Mamdani’s agenda includes free city bus service, free child care, government-run grocery stores, a rent freeze for people living in rent-regulated apartments and new affordable housing — all paid for by raising taxes on the rich.

Matt Bennett, co-founder of the centrist Democratic group Third Way, warned that Mamdani’s policies are a political problem for the Democratic Party.

“The fact that Mamdani is young, charismatic, a great communicator — all of those things are to be emulated,” Bennett said. “His ideas are bad. … And his affiliation with the (Democratic Socialists of America) is very dangerous. It’s already being weaponized by the Republicans.”

Mamdani’s age and ethnic background also earned praise from allies across the country. He would be the youngest New York City mayor in more than a century and its first Muslim and Indian American mayor if elected.

After keeping quiet on Mamdani throughout his primary campaign, three of New York’s top Democrats, Gov. Kathy Hochul, House Democratic Leader Hakeem Jeffries and Senate Democratic leader Chuck Schumer, praised the progressive upstart but stopped short of endorsing him after his victory seemed assured.

The Democratic leaders, largely considered moderates, applauded his focus on affordability and said they had spoken with him, although none explicitly said they would support him in the November general election.

Mamdani’s Democratic critics feared that he would make their task this fall and in next year’s midterm elections, which will decide the balance of power in Congress, even more difficult.

The group, Republicans Against Trumpism, a key Democratic ally in the 2024 election, predicted that Republicans would make Mamdani “the face of the Democratic Party, hurting moderates in swing districts and Democrats’ chances of taking back the House.”

In a Wednesday radio interview with WNYC, Mamdani acknowledged that his contest had become part of the national debate.

“It has been tempting I think for some to claim as if the party has gone too left,” he said. “When in fact what has occurred for far too long is the abandonment of the same working-class voters who then abandoned this party.”

Associated Press writers Matt Brown and Joey Cappelletti in Washington and Jill Colvin in New York contributed to this report.