One the other hand, the oft-heard affirmation that Mary can influence her Son to help us necessarily implies that the Son otherwise would be less disposed to do so. In fact, the very concept of a mediator presupposes that there are differences that need to be reconciled between two parties. This leads to the inescapable conclusion that, apart from Mary's mediation, Christ himself would not be perfectly reconciled to us. All this seriously compromises the integrity of his high priesthood.
The church is stuck in a hopeless dilemma wherein either Mary's role is rendered superfluous, or the all-sufficiency of Christ's mediation is diminished. In trying to avoid either of these perceived pitfalls, it has fallen headlong into both."
Elliot Miller and Kenneth R. Samples, The Cult of the Virgin: Catholic Mariology and the Apparitions of Mary, p. 56