All they have to do is commit to not selling weapons and they can wash their hands clean of Israel.
It’s easier for them to mobilize existing Democrats than to chase leftists who probably won’t vote anyway.
Centrists support Netanyahu’s genocide because Netanyahu supports centrist challengers to progressive incumbents.
I can imagine people not voting because of the arms to Israel. I cannot imagine people not voting Democrat if the arms stop. Centrists are apathic on foreign policy.