New York Gov. Kathy Hochul and New York City Mayor Zohran Mamdani may have been side by side at a news conference on Tuesday, but they find themselves on opposite sides of one of the most closely watched congressional races in the nation.

They are split over the key race in the 10th District, pitting incumbent Dan Goldman, backed by the governor, against former City Comptroller Brad Lander, who quickly picked up the mayor's endorsement on Tuesday.

"In a moment when so many New Yorkers, especially working class New Yorkers, are asking themselves who will stand up for them in moments as difficult as this one, I know that the answer is Brad Lander as the next congressman," Mamdani said.

Hochul, who has talked about taking on President Trump and the need for tested Democrats to take control of the House of Representatives, has backed Goldman.

"New Yorkers need experienced fighters in Washington who know how to stand up to abuse of power," Hochul said. "Dan Goldman is exactly that kind of leader, taking on Donald Trump directly and fighting every day for our state, our democracy, and his district."

What to know about Goldman and Lander

Goldman, 49, has represented the 10th District, which encompasses Lower Manhattan and parts of Brooklyn, since 2023.

He is known for his staunch support of Israel in a district that overwhelmingly supported Mamdani in the recent mayoral election.

"I have a very strong support for the state of Israel, and its right to exist as a Jewish state, the only Jewish state in the world," Goldman said recently. "But I have voiced my serious opposition to the Israeli government, and everybody should be able to do that as I have done."

In addition to Hochul, Goldman has also been endorsed by House Minority Leader Hakeem Jeffries and other congressional leaders.

"[Goldman] has been a leader in the Democratic caucus -- fighting to defend our democracy and standing up to make life more affordable for working families across New York City," Jeffries said in a statement. "Rep. Goldman's strong leadership skills are needed in Washington as we protect our democracy and defend the rule of law."

Lander, 56, was elected as comptroller in 2021 after spending 12 years in the City Council, where he co-founded the Progressive Caucus.

Speaking to a packed crowd in Park Slope back on Dec. 10, Lander said he "will fight, not fold" and embraced what he called "Mr. Rogers energy."

"Yeah, it's a Mr. Rogers that stands up, fights ICE and fights Trump and fights Musk and kleptocrats, and fights AIPAC and says this is our neighborhood," Lander said.

Lander has been endorsed by many champions of the progressive movement, including Mamdani and U.S. Sens. Bernie Sanders and Elizabeth Warren.

Mamdani may prove to be thorn in Jeffries' side, pundit says

Political expert J.C. Polanco, a professor at the University of Mount Saint Vincent in the Bronx, said there will be more disagreements between the governor and the mayor over congressional endorsements.

Polanco said Mamdani, the unapologetic democratic socialist, is expected to back candidates he agrees with philosophically, rather than incumbents he doesn't see eye-to-eye with, and, he added, it's not something Jeffries will be happy about.

"The infighting that the far left is going to bring to his incumbents is detrimental to Minority Leader Jeffries' role in wanting to be speaker and getting the Democrats to majority because he has to spend time and resources on defending his incumbents," Polanco Said. "So the Democratic Socialists of America, led by Mayor Mamdani, is nothing but a thorn in the side of the Democrats that want to win the majority because never in the history of American politics have the Democratic Socialists of America added one seat."