The Next Battlefield for N.Y. Progressives? The State Assembly.

ALBANY, N.Y. — In the final days of New York’s legislative session, the state’s progressive left-wing seemed poised to score a surprise victory.

A bill that would empower New York to build publicly owned renewable energy was suddenly back in play, after being given up for dead. It cleared the Senate despite sharp opposition from energy producers, and, after hours of fervent grass-roots lobbying, activists proclaimed they had enough votes in the Assembly for passage.

But the Assembly speaker, Carl E. Heastie, never called the bill to the floor, and the session ended with no vote taken.

The inability to force Mr. Heastie’s hand was a glaring example of how the most left-leaning state lawmakers have hit headwinds this year, but it was not the only one: Proposals to protect tenants from evictions, create universal health care, and seal criminal records all fizzled, while landmark progressive changes made in prior years, like the 2019 bail reforms, drew backlash.

The battle over the renewable energy bill served as a reflection of both the growing strength of the party’s left wing and its limitations, especially in the Assembly, which has been controlled by Democrats since 1975.

Now a new slate of left-leaning candidates — some backed by the Working Families Party, others backed by the Democratic Socialists of America — are challenging Democratic incumbents in the June 28 primary, hoping to win enough seats to push the Assembly to the left.

To that end, they’ve aligned their legislative and campaign efforts, urging lawmakers to commit to items like the renewables bill, or face the wrath of progressive voters in primary elections.

Sarahana Shrestha, a climate activist who is running for State Assembly in the Hudson Valley, estimates that her team has knocked on 25,000 doors in the Kingston-based district she hopes to wrest from the Democratic incumbent, Kevin Cahill, who has held the seat since 1992.

She said that the Assembly’s failure to pass the renewable energy bill illustrated how traditional machine politics has led to a broken and undemocratic system.

“That just worked perfectly in our messaging of what’s wrong with our government — the culture of our government,” she said, adding that good governance took courage: “It’s much safer to say, ‘This thing did not happen, this bill did not pass,’ then to pass something and then probably be hounded about it.”

Ms. Shrestha, who is backed by the Democratic Socialists of America and the Working Families Party, has been endorsed by Representative Alexandria Ocasio-Cortez, who has lent the force of her reputation to races up and down New York primary ballots this year, stirring intraparty conflict.

Mr. Cahill, who leads the Assembly Insurance Committee, called it a “power grab.”

“It’s about a group of people in the Assembly and in the Senate who mostly have just arrived on the scene in the last couple of terms who believe that they should be put in charge of the place,” he said. “And they know they can’t do it unless they occupy more seats.”

The state Democratic Party chairman, Jay Jacobs, argued that the primary challenges revealed the “arrogance” of progressive activists who were too impatient about achieving their goals, and whose efforts he feared would endanger Democrats’ supermajorities in Albany.

“The Assembly has been a progressive body for quite some time, and has enacted a lot of great progressive pieces of legislation,” he said.

The insurgent candidates are hoping to replicate the 2018 primary results in the State Senate, where a group of progressive-minded Democrats successfully challenged a handful of entrenched incumbents, transforming the body and allowing for a string of victories from criminal justice reforms and climate protections to the legalization of marijuana last year.

Seats in the Assembly and Senate will be on the ballot in November, though only the Assembly primary will take place in June.

Primary elections for Senate and congressional seats were delayed until Aug. 23 by the state’s highest court, which appointed an outside expert to redraw lines it said were gerrymandered by Democrats in the State Legislature.

State Assembly lines were also declared unconstitutional, but will not be redrawn until after the election.

Of the 150 Assembly seats up for grabs this year, a handful have attracted considerable interest.

On the Lower East Side, the race to replace Assemblywoman Yuh-Line Niou, who is running for Congress, pits three Democratic candidates who are proud of their immigrant heritage against one another in a district that, for this election, lost a large portion of the Wall Street area and gained parts of the Lower East Side.

Illapa Sairitupac, a social worker and son of Peruvian immigrants, is running there, with the backing of the Democratic Socialists and a smattering of progressive leaders.

Grace Lee, a first-generation Korean entrepreneur, has won the support of Representatives Jerrold Nadler, Hakeem Jeffries and Grace Meng, among others.

The third candidate, Denny Salas, a political consultant, has made the American dream as a Dominican immigrant a centerpiece of his campaign, and has been endorsed by some union and police groups.

In a nearby district, the retirement from the Assembly of Richard Gottfried, the longest-tenured state lawmaker in New York history, set off a dynamic race among a handful of decorated candidates.

In Harlem, the long-serving Assemblywoman Inez Dickens is facing a primary challenge from Delsenia Glover, a housing advocate who is backed by the Working Families Party.

And in the Bronx, Jeffrey Dinowitz of Kingsbridge and Michael Benedetto of Throgs Neck face some of the toughest challenges of their decades in the Assembly.

Mr. Benedetto, who chairs the Assembly Education Committee, helped broker negotiations that delivered two years of mayoral control of city schools — a power-sharing agreement between the city and state — to Mayor Eric Adams of New York City, who has endorsed him.

Mr. Benedetto’s challenger, Jonathan Soto, has sharply criticized mayoral control, which he says cedes too much power to the executive at the expense of parents.

For Mr. Dinowitz, who chairs the powerful Codes Committee, which oversees changes to criminal and civil law, the threat comes in the form of a first-time candidate, Jessica Altagracia Woolford.

Mrs. Woolford, who worked as a staff member for Senator Kirsten Gillibrand and former Mayor Bill de Blasio, built a mutual aid network during the pandemic that helped deliver groceries to her neighbors in the Bronx.

Her platform is built on extending the mission of that work to statewide issues like climate, health care and housing.

“I see this fight now, in the Assembly, as really essential to make sure that we’re delivering on those progressive values that Democrats are supposed to stand for,” said Mrs. Woolford, who is running with the backing of the Working Families Party.

She is hoping that her enthusiasm, progressive values and Dominican heritage will help her win over a district whose Hispanic population has grown considerably in the 28 years that Mr. Dinowitz has represented it.

Mr. Dinowitz, who has the support of nearly every major union, said he did not believe identity should play a deciding role.

“I think it’s very opportunistic to look at this race based on ethnicity,” he said. “I think most people are smart enough to vote based on the merits.”

He added that he believed his record of championing issues like housing — he was the Assembly sponsor of the state’s pandemic eviction moratorium — and transit access spoke for itself.

Like many of her progressive allies, Mrs. Woolford has benefited from the zeal of left-leaning organizers and the attention of people like Ms. Ocasio-Cortez.

And the low levels of participation expected in the primary election means that energizing even a small number of new voters can have a significant impact.

The stakes have turned some races sour.

In the past week, two super PACs funded in part by real estate interests have spent lavishly, circulating negative mailers about progressive candidates including Mrs. Woolford, Mr. Sairitupac, Ms. Shrestha and Mr. Soto, calling them “too extreme.” One spent over $80,000 on Ms. Shrestha’s race alone, according to Board of Elections records.

The National Working Families Party, in turn, has used an independent committee to spend hundreds of thousands of dollars on TV ads and mailers, some of which paint incumbents as in the pocket of corporate donors.

Incumbents were largely incensed by this framing, and several said the left was imposing purity tests that manipulated facts to fit a political narrative.

“You don’t just say no because you didn’t get every single thing you want,” Ms. Dickens of Harlem said. “That’s not how you negotiate. That’s not how you’re going to navigate through any of the three levels of government.”

She added: “When they get in power, what are they going to do different?”

Mr. Cahill said he backed the public power bill, but that he believed that much of the disenchantment over it was based on a distortion of the measure.

He said that while the left framed the legislation as an environmental bill, he viewed it as more of an economic one, because of the impact it would have on the state’s energy market.

The Assembly will hold a hearing on the legislation on July 28, a month after the primary vote. Though it’s unclear whether it will proceed, progressives like Ms. Shrestha see the extended conversation as progress.

“Whatever we did to make Albany scared of the climate movement this time around, we want to do the same for health care, we want to do the same for housing,” she said.