The public support for Israel comes from political leaders like Biden giving them unconditional support. He isn’t “pressuring” them because there’s absolutely no limit to his support for Israel. Pressure requires some threat of action against them and the US would never do anything like that.
Though you’re right that his Party would revolt if he actually tried applying real pressure on Israel (as opposed to pure rhetoric) but that’s just proof his Party also supports genocide.
And yes, it’s genocide. Look at the definition. “Ethnic cleansing” is just a euphemism that implies Palestinians are filth that need to be cleaned. Call genocide, genocide.