How much room is there after an offer? - first time posting

I received an offer as a warehouse supervisor and I think the pay is a little low. I would rather hear the honest version than the polite one. I have a competing interview next week. What wording worked?

Most employers expect a short conversation. Mine did not even blink.

I thanked them and said I was excited but hoped we could talk about the pay. They came back with a bit more.