A Republican Jewish mother-of-seven and former IDF soldier has lost a special House election in New York to a former Democratic congressman.

Mazi Pilip was beaten by Tom Suozzi for the vacant seat of disgraced congressman George Santos, who lied about his Jewish ancestry and was expelled from Congress at the end of last year.

The win, in New York's 3rd congressional district narrows the Republican majority in Washington to six seats - now 219 to 213 - and may offer Joe Biden a glimmer of hope of winning suburban swing areas in November’s presidential election.

During his victory speech, Suozzi took a shot at Trump and his allies.

“Stop running around for Trump and start running the country,” he said. “It’s time to find common ground.”

However in a blow to Biden, Suozzi during his campaign confessed "I don't think Joe Biden campaigning for me would help" and said "the president is underwater in this district".

Pro-Palestinian protesters stormed the stage just as Suozzi was about to speak, but were quickly escorted out.

Distancing himself from his party during the campaign, Suozzi called for harsher border policies and vowed to work with Republicans to fix a broken immigration system. He called for Biden to temporarily close the southern border.

Ethiopian-born Israeli Pilip made the border issue the centerpiece of her campaign. More than 170,000 migrants have arrived in New York and the police commissioner warned that a “wave of migrant crime” had “washed” over the city.

"This race could be a bellwether for swing suburban districts around the country that are going to decide who controls the gavels of Congress," said Lawrence Levy, executive dean at Hofstra University's National Center for Suburban Studies.

After calling Suozzi to congratulate him, Pilip said: “We will continue to fight.”

The Suozzi campaign spent $10 million in attack ads about abortion. They ultimately outspent Republicans on TV two to one.

Suozzi, who has visited Israel on a post-October 7 solidarity visit, also focussed on defending Israel, cutting taxes, crime and abortion rights.

With 52% of votes counted in the Queens and Long Island district, Suozzi had won 59% of the vote compared with 41% for Pilip, according to The Associated Press.

It is a return to the seat for Suozzi who gave it up in 2022 for an ill-fated run at New York Governor.