I don't even think the motivation is primarily about maintaining military support - it's already a given. Even if the US political regime swung far to the left,

I don't even think the motivation is primarily about maintaining military support - it's already a given. Even if the US political regime swung far to the left, there's simply no chance they aren't going to bat for Israel in an full scale military conflict. I suspect their spying is much more motivated by anticipating and influencing political and economic events or policy that they have second order interests in - ie trade policy, foreign investments, relationship with China, etc.