U.S. Vice President JD Vance and U.S. Secretary of Health and Human Services Robert F. Kennedy Jr. gesture onstage during the inaugural Make America Healthy Again (MAHA) summit in Washington, D.C., U.S., Nov. 12, 2025.

Nathan Howard | Reuters

A Supreme Court case and a bill moving through Congress this week are set to test the bonds of Republicans and the Make America Healthy Again movement, following a near-rupture in February over the weedkiller glyphosate .

The court will hear a case Monday to decide whether federal law preempts state-level lawsuits alleging glyphosate, the chemical in Bayer's herbicide Roundup, causes cancer. And the U.S.…