He could stop sending a new shipment of the very weapons used to commit genocide with every day and a half.
It might not stop it immediately, but it would at least make it more difficult for Netanyahu’s fascist apartheid regime to keep blowing the shit out of innocent civilians if they have to look elsewhere for the bombs to do so with.
Plus, there’s hardly any way to be more clearly an accomplice to war crimes than insisting on sending weapons to be used to commit war crimes regardless of congressional approval.