He has, but Trump knows that he needs the Senate and House to get things done. So he needs to keep them close, if he attacks them, then Trump will be fighting alone in DC. If you watch Trump closely, you would see that he sing praises about everyone, even the people he doesn't like.However, if those people go out and attack him, Trump attacks them. examples - John Bolton, Omarosa, Mad Dog Mattis...etc...Trump sang praises about all of these people first, and then when they turned on him, Trump started attacking them. There are plenty examples like this.