Right now, our tax dollars and American-made weapons are being used to perpetrate a genocide in Gaza, illegal settlements in the West Bank and Jerusalem, and the attempted annexation of Southern Lebanon. That must end. I support immediate and comprehensive enforcement of U.S. laws that condition the provision of military aid and sales. And I support an immediate arms embargo on Israel and reject the false differentiation between “offensive” and “defensive” weapons.

From his campaign website. That's a seismic shift from decades of bipartisan, unflinching support for Isrsel. There is no way to actually enact that policy that doesn't start with getting more people who support it in power.