The victory of Chris Rabb in a US House of Representatives primary in Pennsylvania represents a boost to Democrats’ progressive flank, a movement that has come under heavy pressure in recent years.

Running to represent a district stretching across Philadelphia, widely considered the “bluest” in the country, Rabb handily defeated his top competitors. The state lawmaker carried about 44 percent of the vote, compared with about 30 percent for State Senator Sharif Street and 24 percent for paediatric surgeon Ala Stanford.

With no Republicans on the ballot in the primary, Rabb is expected to skate to victory in the midterm.

While all candidates sought to highlight progressives’ bona fides in the race, Rabb skewed farthest left, railing against the political machinery that has long played kingmaker in local politics.

He also broke from his opponents on US policy towards Israel. He has pledged to join 12 current members of Congress in signing a resolution recognising the Nakba and has urged his competitors to describe Israel’s actions in Gaza as a “genocide” on the campaign trail.

In one exchange with voters, Stanford appeared to say that using the term “genocide” was “harmful”. Street, whose victory would have made him Philadelphia’s first Muslim member of Congress, has also been criticised for a lack of clarity on the issue.

In a statement, Kendra Brooks and Nicolas O’Rourke, cochairs of the Pennsylvania Working Families Party, said the race was a weathervane for Democrats.

“The question in this race was not whether we would elect a Democrat, but what kind of Democrat we would choose,” they said.

“The people of Philadelphia made their choice clear: bold, working-class leadership, and an end to the broken status quo.”

Indeed, the race in many ways mirrored internal strife for Democrats, kicked into overdrive following the party’s routing in the 2024 election.

Street, the former chair of the Pennsylvania Democratic Party, and Stanford, who was endorsed by outgoing Representative Dwight Evans, have largely been viewed as representing the party’s longstanding establishment.

Underscoring that perception, earlier this Month, Axios reported that Pennsylvania Governor Josh Shapiro had urged building unions supporting Street not to run attack advertisements against Stanford, over concerns it would boost Rabb’s chances.

Rabb, meanwhile, had been endorsed by a series of progressive stalwarts, including Representatives Ocasio-Cortez, Representative Ilhan Omar and Senator Chris Van Hollen and progressive groups, including Justice Democrats and the Sunrise Movement.

The Socialist Democrats of America, who endorsed Rabb early on in the race, have been largely credited with leveraging their ground operation before the primary win.

“We will be with Congressman Rabb every step of the way in the fight to abolish ICE (Immigration and Customs Enforcement), free Palestine and win Medicare for All,” the group said on Wednesday.

Progressives targeted

Rabb’s win represents a sign of hope for progressives, who have been heavily targeted in primary races, particularly for their criticism of Washington’s longstanding support for Israel.

In 2024, both Cori Bush of Missouri and Jamaal Bowman of New York, members of the so-called Progressive “squad” in Congress, lost their primary races amid a massive influx of spending by AIPAC and pro-Israel lobby groups. All told, AIPAC and affiliated groups spent about $25m to unseat the pair.

Progressives have so far seen a mixed bag this primary season. Analilia Mejia saw an early surprise victory when she defeated former Representative Tom Malinowski in February.

Malinowski, who has long portrayed himself as a centrist, was targeted by AIPAC in the 11-way race, in a strategy that has been viewed as a major backfire for the pro-Israel lobby. Instead of boosting a pro-Israel candidate, AIPAC’s targeting indirectly buoyed Mejia, a staunch critic.

In Texas, pro-Palestine pastor and civil rights leader Frederick Haynes III also won his primary race. Haynes was also endorsed by the Justice Democrats, an organisation launched in 2017 to support progressive candidates. The group has endorsed 15 candidates so far this year.

Three other progressive candidates, Junaid Ahmed and Kat Abughazaleh in Illinois, and Nida Allam in North Carolina, lost their primaries amid a massive onslaught of opposition spending from pro-Israel and artificial intelligence-aligned groups.

Still, Justice Democrats spokesperson Usamah Andrabi said Rabb’s victory was an energising sign before a slate of competitive races in June.

Also in Pennsylvania, incumbent Representative Summer Lee easily sailed to victory in her Democratic primary race in Pittsburgh.

“The sky is the limit,” Andrabi told Global News Insight, “and it is clear that the Democratic base is desperate for a new generation of leadership that not only takes on Republican extremism but takes on the Democratic establishment and their corporate backers all at once.”

Battlelines draw

Tuesday’s primaries across six states saw the battle lines for the midterm election in November further drawn.

The vote will determine which party controls the US Senate and the US House of Representatives, which will set the pace for US President Donald Trump’s second term in office.

Most notably on the Republican side, US Representative Thomas Massie lost his primary race to Trump-backed challenger Ed Gallrein, in what was the most expensive House primary race in history.

Massie had broken with Trump on the investigation into billionaire financier Jeffrey Epstein, the war in Iran, and US support for Israel. His loss indicated Trump’s enduring hold over the party.

But it remained to be seen if that influence would extend to the general election, with Trump’s approval ranking tanking in recent months amid the war with Iran and its knock-on economic fallout. Polls have shown the president’s support has been particularly hard hit among independents, who typically do not vote in primaries.

In Georgia, two Republicans, Congressman Mike Collins and former football coach Derek Dooley, will advance to a run-off election on June 16 in the US Senate race. The winner will take on Democrat Jon Ossoff in one of the closest-watched races of the season.

Meanwhile, Democrat Keisha Lance Bottoms, the former mayor of Atlanta, won the party’s primary in the gubernatorial race. Two Republicans, Rich Jackson and Burt Jones, meanwhile, will head to a run-off.

The race is set to be consequential, with election administration – and the redrawing of congressional maps – in the state looming large in 2024 and potentially set to play a key role in the 2028 race.