Having a very hard time due to lack of discipline and support

Hey everyone, I'm a student teacher (graduate school) currently in a kindergarten classroom. I am really struggling with classroom management. The students seem to be very very unruly and the mentor teacher is not very nice to them and kind of lets them walk all over her. She is not very good at redirection techniques. I am really having trouble with one particular student and am wondering some ways to also work with kids who hit and push. I feel like my anxiety is getting really bad bc I just feel so out of control in the classroom and there is not much support for me.