New York City Mayor Zohran Mamdani is wielding his office to install ideological allies in Congress, endorsing three left-wing challengers to sitting Democratic incumbents, and drawing sharp rebukes from members of his own party who say the mayor is repaying loyalty with betrayal.
The targets are Democratic Reps. Dan Goldman in New York's 10th Congressional District, the open seat in the 7th District, and Adriano Espaillat in the 13th. The challengers, Brad Lander, Claire Valdez, and Darializa Avila Chevalier, share Mamdani's democratic-socialist orientation. Two of the three carry endorsements from the New York chapter of the Democratic Socialists of America, the largest socialist organization in the country. If Mamdani's slate wins, DSA representation in Congress would double.
That prospect has forced House Minority Leader Hakeem Jeffries to divert resources away from flipping Republican-held seats and toward defending his own incumbents, an extraordinary internal drain during a cycle in which Democrats are trying to recapture the House majority.
The most visible clash is in NY-10, where Mamdani has backed former city comptroller Brad Lander against two-term Rep. Dan Goldman. The backstory is personal. Goldman declined to endorse Mamdani's mayoral bid, citing concerns about the mayor's posture toward antisemitism. Goldman did not vote for Mamdani in the general election.
Now Mamdani is returning the favor. Fox News reported that the mayor endorsed Lander's congressional challenge immediately upon Lander's campaign launch, calling Lander a "trusted ally and partner" whose "unwavering principles, deep knowledge, and sincere empathy are what make him a true leader."
Goldman, for his part, had asked Mamdani to take concrete steps to protect Jewish New Yorkers. His exact words, as Just the News reported:
"I have asked him to consider taking serious and concrete action to demonstrate that he is going to make sure that Jews are protected and are secure in our city, and I hope he does that."
Mamdani's record on that front is thin. The day after the October 7, 2023, Hamas terrorist attacks, then-state Assemblyman Mamdani posted a statement on X that made no mention of Hamas and included condemnation of Israel only.
Lander, himself Jewish, has made opposition to Israel's campaign in Gaza the centerpiece of his congressional bid. At a campaign event earlier this month, he declared: "As a proud Jewish New Yorker, I will join you in that fight to end occupation and apartheid and genocide." He has pledged to oppose additional U.S. military aid to Israel and attacked Goldman for accepting AIPAC donations.
An Emerson College poll conducted last month showed Lander leading Goldman by 34 points, 57 percent to 23 percent, with 20 percent of the district still undecided. If those numbers hold, Goldman's seat is already gone.
In the 7th District, Mamdani endorsed New York Assembly member and union organizer Claire Valdez, a DSA-backed candidate whose platform reads like a socialist wish list. Her campaign website calls for abolishing ICE, legalizing "millions of immigrant Americans," enacting Medicare for All, pursuing "Queer and Trans Liberation," imposing universal rent control, and ending all weapons sales and military aid to Israel.
Valdez faces Brooklyn Borough President Antonio Reynoso, who is backed by outgoing Rep. Nydia Velazquez and runs on his own progressive platform. Even in a district where both candidates lean left, Mamdani chose the one carrying the DSA endorsement.
Mamdani's approach to housing policy, including a plan to strip buildings from landlords and hand them to tenants, mirrors the kind of agenda Valdez would bring to Washington. The common thread is not incremental reform but structural transformation of property rights and federal spending.
In the 13th District, the mayor endorsed Darializa Avila Chevalier, another DSA-backed democratic socialist, against Rep. Adriano Espaillat. Espaillat has represented the Upper Manhattan district for nearly a decade and leads the Congressional Hispanic Caucus.
What makes the Espaillat challenge especially bitter is the timeline. Espaillat initially backed former Governor Andrew Cuomo in the Democratic mayoral primary last year, then switched to endorsing Mamdani. Mamdani won. Now the mayor is backing a challenger to the man who helped put him in office.
Rep. Juan Vargas, a California Democrat, did not hold back about the Espaillat situation:
"I think it's outrageous. Here we have the leader of the Hispanic Caucus, who has worked hard in his position, a very progressive guy, and all of a sudden he's cut off at the knees by the mayor, who told him he was going to support him."
That claim, that Mamdani privately assured Espaillat of his support before endorsing Avila Chevalier, hangs in the air without a public denial from the mayor's camp. If true, it suggests a pattern not just of ideological ambition but of personal dishonesty.
Mamdani has shown a willingness to punish anyone who steps out of line. An NYPD captain was recently stripped of command after publicly criticizing the mayor, a move that raised questions about whether Mamdani tolerates dissent from anyone under his authority.
The mayor's combative streak extends well beyond personnel. His renewed calls to abolish ICE, issued after protesters attacked federal agents outside a Brooklyn hospital, put him at odds with federal law enforcement and alarmed even some Democratic allies.
Those close to Mamdani describe his endorsements as part of an attempt to "radically" reorient the Democratic Party. Faiz Shakir, an advisor to Senator Bernie Sanders and a friend of the mayor's, framed it in aspirational terms:
"He's seeing that opportunity, that we can radically change the Democratic Party. Like Bernie, he's not saying I'm doing this out of spite against you, dear leadership. He's saying, I am supporting these candidates who have a better vision, and I am prepared to lose if it has to be the case."
Shakir's comparison to Sanders is revealing. Sanders ran two presidential campaigns that pulled the Democratic Party sharply leftward on health care, college tuition, and wealth taxation. Mamdani appears to be running the same playbook at the municipal level, using the mayor's office as a launchpad for national ideological influence.
Democratic strategist Rebecca Katz, whose firm worked with Mamdani during the mayoral election, told NBC News: "This is high-risk, high-reward. He's not afraid to take some big swings."
High-risk for whom? For Mamdani personally, the downside is limited. He already holds the mayoralty. If his candidates lose, he still runs the city. If they win, he gains a congressional bloc that shares his agenda on Israel, immigration, housing, and the welfare state.
The risk falls on Jeffries and the broader Democratic caucus. Every dollar spent defending Goldman and Espaillat in safe blue districts is a dollar not spent competing for swing seats. Jeffries acknowledged the situation to Punchbowl News with careful restraint:
"I trust the voters to make the right decision in all of these different races. I, of course, will continue to aggressively support Congressman Espaillat and Congressman Dan Goldman."
That statement reads less like confidence than damage control.
Mamdani leaned heavily on DSA backing to win both the Democratic primary and the general election last November. The organization's infrastructure, its volunteers, its donor networks, its social media reach, helped propel a democratic socialist into the mayoralty of the largest city in the country. Now that infrastructure is being deployed to reshape the city's congressional delegation.
The Fox News report noted that NYC Councilmember Chi Ossé abandoned a primary challenge against Jeffries himself after failing to secure endorsements from Mamdani and the DSA, a detail that suggests the mayor now functions as a gatekeeper, deciding which left-wing challengers run and which stand down.
Other cities have watched this dynamic play out. A Seattle Democrat who once cheered a socialist mayor's rise later warned of the business exodus that followed. The pattern is consistent: ideological purity first, governing consequences later.
Several questions remain unanswered. What is the polling situation in NY-7 and NY-13? What specific resources has Jeffries redirected to defend incumbents? And what is the current DSA membership count in Congress, the baseline that Mamdani's slate would double?
What is clear is the scope of the mayor's ambition. Mamdani is not content to govern New York City. He wants to govern the terms on which Democrats from New York City go to Washington. His preferred candidates want to abolish ICE, end military aid to Israel, impose universal rent control, and expand the welfare state. The incumbents they are challenging, already progressive by any national standard, are apparently not left enough.
For Hakeem Jeffries, the math is straightforward and unforgiving. A House minority leader trying to win a majority cannot afford to fight a two-front campaign, one against Republicans, and one against a socialist mayor cannibalizing his own incumbents. Every primary dollar is a general-election dollar lost.
For voters in these districts, the choice is between Democrats who have served in Congress and a slate of candidates selected by a mayor who could not bring himself to mention Hamas the day after the worst massacre of Jews since the Holocaust.
When a party's biggest internal threat comes from a mayor who treats loyalty as a one-way street and ideology as a litmus test, the problem isn't one bad endorsement. It's a machine being built in plain sight.