A leading member of the Left-wing “Squad” of Democrats in the US Congress has lost a costly and bitter re-election battle.

Jamaal Bowman, 48, was routed in a contest for New York’s 16th district that turned into a referendum on progressives’ attitudes toward Israel – and the most expensive House of Representatives primary in American history.

The clear winner of Tuesday’s vote was George Latimer, a pro-Israel centrist, whose financial backers spent almost $15million (£12million) on his campaign.

A congressman for the district since 2020, Mr Bowman’s criticism of Israel’s war on Gaza made him a target for pro-Israel lobbying groups.

He is the first member of The Squad to lose an election since the group – which includes fellow New York representative Alexandria Ocasio-Cortez – was formed in 2018.

A vocal advocate of Israel, Mr Latimer, 70, is likely to win the congressional election in November given the heavily Democratic make-up of the district. Mr Bowman will remain the congressman until that vote.

Mr Latimer benefited from an unprecedented flood of outside cash in a primary which highlighted the Democratic Party’s internal divisions over the Israel-Hamas war.

The American Israel Public Affairs Committee (AIPAC) and an affiliated group, United Democracy Project, spent millions on supportive TV ads for Mr Latimer in a bid to punish Mr Bowman for his criticisms of the Israeli offensive in Gaza.

Mr Latimer hailed the result as a defeat for the hard-Left positions adopted by The Squad.

“There are good men and women in Washington who feel the way we do,” he said. “We have to look at the arguments of the far Right and the far Left and say you cannot destroy this country with your rhetoric.”

For his campaign, Mr Bowman raised plenty of cash from progressive groups, contributing to a cumulative record spend on a House primary of $24.8million.

Following his defeat, Mr Bowman attacked the pro-Israel groups backing Mr Latimer, which he said helped “brainwash” voters.

“Unfortunately some so-called Democrats are aligning themselves with radical, racist Republicans,” Mr Bowman told supporters.

He remained steadfast in his criticism of Israel and support for Palestinians, adding: “We will never stand for the bombing and killing of babies in Gaza.

“Our opponents may have won this round at this time in this race. But this will be a battle for our humanity and justice for the rest of our lives.”

As well as accusing Israel of genocide and flirting with conspiracy theories, Mr Bowman was censored by the House last year for triggering a fire alarm in Congress that upended a critical vote.

United Democracy Project pledged to replicate its backing of Mr Latimer in races across the country against other Israel critics.

A spokesman said: “Latimer’s victory is another example of how support for the US-Israel alliance is both good policy and good politics. UDP will continue to support leaders who promote our partnership with Israel and oppose detractors, regardless of political party.”

Elsewhere, Tuesday’s primaries saw some bad results for Donald Trump, the presumptive Republican presidential nominee.

Trump endorsed Trent Staggs to replace retiring senator Mitt Romney in Utah but Republican primary voters instead picked John Curtis, an occasional critic of the former president.

In South Carolina, Trump’s preferred candidate, pastor Mark Burns, was narrowly beaten by nurse Sheri Biggs in the Republican primary for a congressional seat.

In Colorado, Trump endorsed local Republican party chairman Dave Williams despite him sending an email titled “God Hates Pride” that described LGBTQ+ people as “godless groomers” and “creeps”. He lost heavily in a congressional primary to conservative commentator Jeff Crank.

Across the state, however, there was a more positive outcome for Mr Trump.

Republican Congresswoman Lauren Boebert won a primary after she decided to run in a different district from the one where she narrowly won re-election in 2022.

The 37-year-old has built a national profile as a conservative firebrand and staunch supporter of Trump.