To be of one mind with someone.
To be of the same opinion as someone.
To share the same view as someone.
To be at one with someone.
To go along with something.
To give the go-ahead to something.
To give the green light to something.
To give the thumbs-up to something.
To rubber-stamp something.
To strike a bargain with someone.
To clinch something.
I hope that this helps.
Les