One the deal is made, now the real challenges of negotiation being with the two levels being very, very hard to move.

BTW, very eloquent response to a politically charged question.

It’s hard to know a priori that the dates are irrational. If I can take the scenario you gave me, in those stark terms, and assuming we’re talking about a new project rather than one I’m thrust into, I’d most likely say something like this:

After listening to what you’re telling me about the objectives of the project and its utility, and taking it to heart for a while, you know what I think? This might be way too ambitious for the delivery date you expect. I don’t have an exact measurement, but is extending the delivery date at all possible? (If yes:) Okay, let’s discuss that in more detail… (If no:) To make sure we don’t completely shatter your expectations, let’s make a list of the benefits (or deliverables, or value items, or features) and rank them by priority. And let’s draw a line where the stuff under it might not get done. If we got everything above the line done by date X, would that work for you? No, seriously?

It depends a lot on the conversations that led up to that point, of course, but that’s the basic idea. Also, I bring bagels.

I’m sure you’ve faced situations like that, John. What do you do?