Ironically, that was one of the biggest campaign points and voter sentiment on which people flipped to Red. We all know what happened.
On the other hand, there is no guarantee that completely cutting off ties with Israel, would make anything better for Gazans. While it's possible there would be fewer civilian casualties, it's also possible there would be more if Israel switched to from precision strikes to ground invasions and dumb weapons.
How would “dumb” bombs be worse?
Syria killed 10,000s of civilians in just a few weeks using only dumb artillery to shell a city: https://en.wikipedia.org/wiki/1982_Hama_massacre
The American incendiary bombing of Tokyo killed 100,000 people in a single night of bombing: https://en.wikipedia.org/wiki/Bombing_of_Tokyo_(10_March_194...