AOC is backing a primary challenger to Sean Patrick Maloney, a fellow New York Democrat and the head of the party's House campaign arm

• AOC is backing state Sen. Alessandra Biaggi against fellow Democratic Rep. Sean Patrick Maloney.
• The endorsement pits a leading progressive against the head of House Democrats' campaign arm.

Democratic Rep. Alexandria Ocasio-Cortez of New York is backing state Sen. Alessandra Biaggi in a primary challenge against fellow Sean Patrick Maloney, a fellow House Democrat from New York and the chair of the party's House campaign arm.

Following her election in 2018, Biaggi, 36, became an influential progressive representing a sprawling Bronx district. She was at the forefront of efforts to remove former New York Gov. Andrew Cuomo from office in 2021, and she was a vocal critic of the three-term governor on issues like COVID-19 nursing home deaths beforehand.

"Alessandra has been here before — she knows what it takes to go up against powerful opponents and win," Ocasio-Cortez said in a fundraising email. The news was first reported by the New York Times.

The decision by Ocasio-Cortez to buck Maloney, who's currently serving a second term as the chair of the House Democratic Campaign Committee, comes after the congressman angered progressives and other Democrats last month by announcing that he would be run in a district currently held by Democratic Rep. Mondaire Jones of New York.

Biaggi and Maloney will face Democratic primary voters on August 23.

Maloney chose to run in a district to the south of the reworked version of his current one in the Hudson Valley, the 18th district. By running in the 17th — which will cover some of the wealthy suburbs to the north of New York City on both sides of the Hudson River — he picked a much safer district, with a 7 percentage point partisan lean favoring Democrats instead of a 3 percentage point one in his old district, according to FiveThirtyEight.

Maloney's campaign provided Insider with internal polling data indicating that 45% of the district's voters back him, while just 15% backed Biaggi, who represents a state senate district far outside the district; 76% said they were unfamiliar with her. The poll was conducted by Global Strategy Group over May 26 - June 1 and included 385 likely Democratic primary voters, with a margin of error of 5 points.

Some Democrats argued that Maloney should have stayed in the competitive district further to the north that included much of his old one.

Maloney has insisted that the district is his to run in, given his residency in Cold Spring within the newly-drawn boundaries.

Jones — a first-term progressive congressman and one of two Black, gay members of Congress — later opted to run instead for a newly-created open seat in New York's 10th congressional district, which covers Lower Manhattan and parts of Brooklyn.

Biaggi had previously been running for an open seat that encompassed parts of Long Island and Westchester County before opting to challenge Maloney.

"His job is to maximize the number of seats that we have in the Democratic majority and if he was doing his job, he would have stayed in that district," she told the Times, referring to the more competitive district that Maloney had mostly represented before.

Biaggi told the Times that she was "thrilled" to have Ocasio-Cortez's support. She'd already received the backing of Democratic Rep. Jamaal Bowman of New York, another progressive "Squad" member.

"Her endorsement is really an indication to everyone that this is an important fight for the party," Biaggi said. "She really is the standard-bearer."

In a statement to Insider, Maloney offered praised for Ocasio-Cortez but said he would have to "agree to disagree" on the congresswoman's decision to back his primary opponent.

"I respect Rep. Ocasio-Cortez and have worked with her on a number of policy matters, including as a co-sponsor of the Green New Deal," he said. "But, on her endorsement, we are going to have to agree to disagree."

He added, "This election comes down to voters in NY-17, and I am honored to have received overwhelming support locally, including endorsements from nearly 40 elected leaders and democratic party committees."

Biaggi's father, Mario, served in the House from 1969 to 1988. Facing expulsion amid corruption charges brought by Rudy Giuliani, then the US Attorney for the Southern District, he resigned and subsequently served 26 months in prison.