Brad Lander, the outgoing comptroller of New York City, announced Wednesday that he is running for Congress, challenging U.S. Rep. Dan Goldman in a Democratic primary for a liberal district in lower Manhattan and northwest Brooklyn.

Lander, a progressive ally of Mayor-elect Zohran Mamdani, launched his campaign in a video and social media posts, promising to offer “courageous leadership in the face of Donald Trump’s attacks on New Yorkers.”

“At a moment of dark oppression, we can shine by fighting back together,” he said. “While the oligarchy drives an affordability crisis, they shouldn’t be able to buy a seat in Congress. While our immigrant neighbors are being demonized and attacked, we can put our bodies on the line to protect them,” said Lander in the video.

He also evoked the late children’s TV host Fred Rogers, singing “Would you be mine? Could you be mine? Won’t you be my neighbor?”

“I know it’s corny, but I love the idea that democracy is just neighbors working together to make our lives in common better,” said Lander, who scheduled a public speech about his campaign Wednesday evening near his home in Brooklyn.

Lander has been eyeing a challenge to Goldman since he lost the Democratic mayoral primary to Mamdani this summer.

In his endorsement, Mamdani praised Lander’s “unwavering principles, deep knowledge, and sincere empathy.”

“He has been a trusted ally and partner of mine and I’m proud to support him as I know he’ll continue delivering for those who need government to show up for them the most,” Mamdani added.

Both Lander and Goldman have been vocal critics of the federal government’s deportation agenda, appearing at a high-profile immigration court in Manhattan to observe proceedings over the last several months.

Lander was arrested there twice and faces a misdemeanor obstruction charge stemming from one of the incidents.

Vermont Sen. Bernie Sanders also endorsed Lander, stating, “Brad Lander is a relentless fighter for working people.”

Goldman, a two-term congressman, is a former federal prosecutor who was lead counsel for Trump’s first impeachment. He is considered a moderate Democrat, though he has supported raising taxes on wealthy individuals as well as the Green New Deal climate change proposal.

An email seeking comment was sent to Goldman’s campaign.

Lander, who is also a former city council member, will leave office as comptroller next year after deciding not to seek reelection.

Lander and Mamdani endorsed one another during the mayoral primary in an effort to join forces against former Gov. Andrew Cuomo, who at the time was the front-runner.

The partnership helped them both, with Mamdani’s support boosting Lander among the progressive base, while Lander’s backing assisted Mamdani amid criticisms over his stance on Israel.