It's hard negotiating salary. I had an offer this year and was unhappy with the salary. I pushed the Dean as far as I could stating things such as, "I am very thrilled at the prospect of joining the faculty at XYZ University, the salary is lower than I was expecting. I had $xx,xxx in mind," or "my current salary is $xx,xxx can you get close to it?" and lastly, "according to the AAUP salarly figures, your competition (other SLAC or R1) pays $xx,xxx can you come up from your original offer?"
My story was that I eventually turned down the position because the match and quality of life issues weren't quite right (and I was reasonably sure I had another offer in hand). I did mention that the salary was low during the conversation. At that point, after I had already declined the offer, the Dean sounded like he could have thrown in a grand or two more. So you could always try to play hardball, but becareful because they could tell you to go take a walk.