Fiercely fought primaries on August 4 in Michigan and Missouri will provide the next crucial tests in the debate over American policy toward Israel that has convulsed the Democratic Party this year.

Arguments about Israel have marked a sharp dividing line in both the Michigan Senate primary between centrist Rep. Haley Stevens and progressive Abdul El-Sayed, and a Missouri rematch between firebrand former US Rep. Cori Bush and Rep. Wesley Bell, a more mainstream figure, who ousted her in a primary two years ago. While Stevens and Bell largely defend the existing US security partnership with Israel, El-Sayed and Bush denounce it.

For years, critics of Israel like Bush and El-Sayed were largely marginalized in the Democratic Party. But the party’s primaries this year have demonstrated an explosion of frustration among rank-and-file Democratic voters over Israel’s actions in Gaza, the West Bank and elsewhere under long-time Prime Minister Benjamin Netanyahu — and the refusal of former President Joe Biden to more forcefully confront him while in office.

The intensity of that backlash has rapidly reset the terms of the Democratic debate over Israel. Only two years ago, Democratic presidential nominee Kamala Harris refused to allow a pro-Palestinian activist to speak from the podium at the party’s national convention. Today, Democrats are debating not whether, but how extensively, to reconfigure American policy toward Israel and the Palestinians.