The United Democracy Project, an AIPAC-affiliated Super PAC, has spent about $11 million to support Stevens or oppose El-Sayed ahead of the August 4 primary.
"We are trying to ensure that pro-Israel Democrats have a voice in the primary process," said Patrick Dorton, a spokesman for the AIPAC Super PAC.
"There is an insidious attempt by fringe left socialists to drive pro-Israel Democrats out of the party.
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We are not going to let what happened to the Labour party in the UK happen to the Democratic party in the United States."
Progressives have secured recent congressional primary victories in New York, Colorado, and New Jersey, but establishment candidates backed by pro-Israel funding have also won races, including Adrian Boafo in Maryland.
"There isn't a one-size-fits-all answer," said Tali deGroot, vice-president of political and digital strategy for J Street, a liberal pro-Israel and pro-peace lobby group.
Former Congressman Andy Levin, who lost his seat to Stevens in 2022 after extensive AIPAC spending, noted that positions on Gaza have become a baseline test of authenticity for many voters.
"There's something about taking a position on Israel, Palestine and Gaza that is about authenticity," Levin said.
"The Gaza issue almost exemplifies now the questions about authenticity and truth-telling in politics that people care about."
Democratic Socialist Wisconsin State Representative Francesca Hong said voters increasingly connect international military expenditures to domestic economic pressures.
"Voters understand that a politician unwilling to fight against the massacre of children abroad (which we're funding), they won't stand up for folks back home," she said.
Darrin Madison, another Wisconsin state representative, identified affordability and the influence of special interest groups in buying elections as top concerns among constituents.
"If you aren't willing to take that stance, what other communities are you willing to abandon?" he asked.
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"Is that folks of color, rural communities, working-class communities?"
