US House Democratic Whip Katherine Clark won her party's primary in Massachusetts' 5th Congressional District, defeating two progressive challengers who had sought to make Gaza policy and pro-Israel campaign funding the central issue of the contest. The result illustrates the wider strain within the Democratic Party over its stance on Israel's conduct in the Gaza war, even as Clark, the second-highest-ranking House Democrat, comfortably retained her safely blue Boston-area seat.

Clark, first elected in a 2013 special election and Whip since 2022, beat Jonathan Paz and Tarik Samman, both union organisers who criticised her for accepting funding linked to AIPAC, the pro-Israel lobbying group, despite her growing criticism of the Israeli government. Her campaign vastly outspent both rivals, raising $4.5 million against Paz's $88,500 and Samman's $43,800. While AIPAC has backed her, Clark voted in July to cut $3.3 billion in US military aid to Israel, arguing Prime Minister Benjamin Netanyahu's government had failed to meet American interests, and previously used the word "genocide" before clarifying she was not accusing Israel of it directly.