Now, that assemblyman is the most powerful Democrat in America’s most powerful city, who, on Tuesday, went three for three in congressional endorsements.

All three of the Democratic Socialist’s endorsed congressional candidates won their primaries, including two who unseated sitting Democratic incumbents. Former city comptroller Brad Lander defeated Rep. Dan Goldman in NY-10; 32-year-old first-time candidate Darializa Avila Chevalier, an investigator at a public defender’s office, ousted five-term incumbent and Congressional Hispanic Caucus Chair Rep. Adriano Espaillat in NY-13; and the Mamdani-backed state Assemblywoman Claire Valdez beat out Brooklyn Borough President Antonio Reynoso in NY-7, the latter of whom was endorsed by outgoing Rep. Nydia Velázquez. All three will almost certainly win in November in their deep-blue districts, placing three Mamdani allies in Congress come January.

The sweep was the clearest show of force yet of Mamdani’s political power, just six months into office. Treasury Secretary Scott Bessent wasted no time Wednesday morning calling Mamdani “the leader of the Democratic Party.” Bessent may have very well said what every business leader, from Midtown Manhattan in Mamdani’s own backyard to those who left for Miami might be thinking: Is Tuesday night’s win a New York story, or evidence of something larger?

“There’s a tide across the country that’s an economic populist tide,” said Ben Max, director at New York Law School’s Center for New York City and State Law and host of the Max Politics podcast, and one of the most closely watched voices on New York politics. “There is a deep frustration among many Democrats with the Democratic establishment and leadership—many Democrats blame the establishment for the second Trump presidency, and there’s a real sense of dissatisfaction with the old guard.”

“A part of that is this question of fighting inequality, fighting corporate power, and many Democratic voters, especially in the left wing of the party, wanting to see elected officials who will be more responsive to everyday people than wealthier interests,” Max continued.

The results aren’t a coast-to-coast mandate for democratic socialism. In Utah, a moderate Democrat crushed progressive challengers in a redrawn safe blue seat. In the competitive New York suburbs, moderate Cait Conley won the nomination for a pivotal House race against Republican Rep. Mike Lawler. For this, Max said the left-wing surge “was mostly limited to races where Mamdani was involved.”

But that limitation may itself be what the C-suite is concerned about. Mamdani isn’t a symptom of a broad ideological wave: He’s evidence of what a disciplined, high-charisma local politician with a populist economic agenda can do when he decides to go on offense. And now, it’s going national.

“We’re already seeing the rise of more left-wing mayoral candidates, Senate candidates—economic populists running for a variety of seats who are talking about a more progressive tax code, taking on inequality and the wealth gap,” Max told Fortune. “This is only growing in momentum right now.” The Trump administration’s tax-and-spend package, he added, is only handing those candidates more material to work with.

The business community’s first instinct was panic

When Mamdani first won the Democratic mayoral primary in June 2025, corporate New York quickly became alarmed.

“The reaction of the business community to the victory of a member of the Democratic Socialists is a combination of surprise and deep concern,” Kathryn Wylde, CEO of the Partnership for New York City—a nonprofit representing executives from JPMorgan Chase, BlackRock, Goldman Sachs, Verizon, Pfizer, and roughly 300 other leading companies—told Fortune at the time.

Hedge fund manager Bill Ackman said he woke up “a bit depressed.” JPMorgan CEO Jamie Dimon called Mamdani “more of a Marxist than a socialist.” Real estate stocks sold off just as threats to relocate to Florida multiplied.

But none of that came: Real estate firm JLL’s first-quarter 2026 data showed Manhattan office leasing activity climbing for top-tier buildings as vacancies declined and rents rose 3.5% year-over-year. American Express announced a new lower Manhattan headquarters; Bank of America signed a new long-term lease; and even Ken Griffin—the hedge fund billionaire Mamdani called out for his proposed pied-a-terre tax—remained committed to a two-million-square-foot office project in Midtown.

Despite the public sentiment, the business community had shifted from resistance to somewhat wary engagement. After his remarks on Griffin generated backlash, Mamdani began a quiet round of meetings with financial and business figures, including Dimon.

“Those relationships are already starting to be either developed or mended in some ways,” Max said. “There’s some uneasy bridge building there.”

But the most uncomfortable signal for those CEOs may be coming from inside the building. An analysis by The City Reporter found Mamdani’s mayoral campaign received more than $242,000 from nearly 2,000 employees at the roughly 300 companies belonging to the Partnership for New York City—the same organization whose leadership spent millions opposing him. Google employees alone, 323 of them comprised mostly of software engineers and researchers, gave more to Mamdani than workers from any other Partnership member company.

A CEO who dismisses Mamdani’s movement could risk alienating the very workforce that keeps companies anchored in New York.

“I do think you’ll see some CEOs look to create better relationships with Mamdani, and realize that he is the most powerful politician in New York right now,” Max said. “He has a movement that is capable of unseating incumbents and winning a lot of elections and influencing others.”

Sights set for Albany

While the congressional results may be what’s on everyone’s minds today, for businesses with a significant footprint in New York, Max warned they should keep tabs on what’s happening at the state level.

“The results of the state legislative primaries in New York are particularly important because there’s going to be a much larger block of democratic socialist state legislators going into next session in Albany,” he said, “where there’s going to be an even more fervent push by Mayor Mamdani and his allies to increase corporate and income taxes in New York.”

This is no more evident than the mayor’s calling on New York Gov. Kathy Hochul to increase taxes on high earners. Hochul has served as the primary check on the mayor’s most aggressive tax proposals, like when Mamdani delivered an ultimatum to the governor to either tax the ultra-wealthy or let city homeowners face a 9.5% property tax hike. Hochul has since held the line on income taxes while agreeing to a narrower pied-à-terre surtax on second homes valued above $5 million. The two have maintained a “fairly collaborative, if at times uneasy, truce,” according to Max.

“Seeing all these state legislative seats shift to the left is going to force her to think about how she’s going to balance maintaining” that position while still drawing Mamdani’s base to the polls in the fall, Max said. He drew the comparison to the Democrats who stayed home in 2024—and to Hochul’s own 2022 race against Lee Zeldin, which was far closer than expected partly because of Democratic turnout failures. Hochul’s strategy, Max predicts, will be to “continue her balancing act”—embracing Mamdani on shared priorities like expanded child care while holding her ground on taxes. Whether that’s viable heading into budget negotiations with a more progressive Albany is the question corporate lobbyists should be gaming out now.

What happens at the state level is more likely to leave a lasting impact on companies than last night’s election results, and that largely has to do with the ongoing threat of high earners fleeing for lower income tax states.

“I think where companies are deciding to expand or open new headquarters is where probably a lot of this next frontier is going to be negotiated and waged,” he said. Legacy companies with deep New York roots are unlikely to bolt, but for companies still deciding where to grow, there’s some additional uncertainty with a more progressive Albany.

What happens to Democrats in Congress?

Often finding himself at the receiving end of questions regarding the new Democratic party’s identity, House Minority Leader Hakeem Jeffries has long defended his party’s less-left-leaning stance. In a tension-filled back and forth with an increasingly severed party, the Brooklyn-native representative even brushed aside the former Queens-assemblymember-turned-mayor’s endorsements, telling reporters “a handful of primaries that go in one direction or the other in a given state or two aren’t going to reshape who we are as House Democrats.”

While Mamdani endorsed two candidates against more moderate incumbents, he was careful not to challenge Jeffries directly. When New York City Council member Chi Ossé filed paperwork to run against Jeffries last year, Mamdani dismissed the idea, saying “the focus should be right here on New York City.” Last night’s results means the minority leader needs to tread carefully as he leads the party.

“Hakeem Jeffries has to pay attention to the trends in his own backyard where he and his political operation just lost more seats,” Max said, “and the trends in Brooklyn and beyond are heading in the progressive direction, and not in his more moderate direction.”

The real test comes after November. If Democrats retake the House with a slim margin, the bloc of progressive and democratic socialist members—Mamdani allies among them—will have significant leverage over the speaker’s agenda.

“Can the next speaker of the House afford to lose half a dozen of the most left-wing members on certain votes?” Max asked. “If the next speaker really needs to keep a very tight Democratic majority altogether, then the socialists and the further left progressives are going to have a lot of power to move the conference.”

Economic development from both fronts

The larger issue business leaders may want addressed is whether Mamdani has an economic growth agenda to match his redistribution one.

“There’s been a lot of questions about Zohran Mamdani having an economic growth mindset and program,” Max said, “and one of the takeaways from this election cycle is that he’s getting a lot of positive reinforcement for what he’s already been doing and saying.”

“That remains an outstanding question—what we’ll see from the administration around their economic development lens and their interest in encouraging private sector growth, and to what extent the mayor sees that as a priority,” he continued.

Mamdani’s team has shown a willingness to negotiate in practice even while pushing for structural change—driving, in Max’s words, “pretty hard bargains” on affordability provisions, child care, and labor standards in land use and tax incentive deals, while “acknowledging that they have to work closely with the private sector.”

When Mamdani brought a mock newspaper front page to the White House to charm Trump into a $21 billion federal housing commitment for Queens, Max said that’s the kind of pragmatic dealmaking that suggests his administration is not purely ideological. The city-run grocery stores and corporate tax fights make for sharp contrasts, but they haven’t stopped the leasing activity or the bridge-building with Dimon.