He definitely has at least the means of applying pressure.
Completely freeze military cooperation and weapon deliveries and withdraw the Carriers they send would be possible after talks failed.
But that is not something that makes sense when you want to keep your military base in the middle east functional and regarding the vast amounts of religious people in the US it would put off parts of potential voters next year.
I think the whole aspiration of a ceasefire is just political talk so the US can say they tried their best, in the end they will support Israel in their more than questionable response to Hamas despicable provocation.
There is a limit. Israel is unhinged in their response.
There should never be unconditional support for anything, good for him to have realized this. May germany follow!