Barry has been around the block a few times.

If he thinks the system can't fly by Jan 1, then it would be stupid for him to volunteer for a death march to the inevitable belly flop.

Personally if I was in Barry's position, I would draw up the different options, and I would offer upper and lower limits to how long he guesses that they would take. Give big error bars, and estimates of what point in each option he would be able to give better estimates. If you want to do well by the President, go up to him and tell him in advance, This is basically what I am going to have to say. But if you can figure out how to say it so that I get the facts across but cause a smaller mess, I will say it that way.

Throw that in everyone's lap. A key point would be, I refuse to touch this project unless people are planning on these figures. If I take this project and people attempt to impose anything else on me, I will drop it again like a hot potato. If you think that anyone else can do it more reliably or faster, let them. Let the crap fall where it may.

My goals would be to first protect the principle that other people's misjudgements shouldn't become your nightmares. Second, make sure that people get bad news early, rather than late, so that they have as long to deal with it as possible. Third, protect your reputation as a person who does what you say you can. Fourth, protect your reputation as a person who can be depended on to say things as they are. Other things come lower.

This won't make the President happy by giving him the politically convenient lie. But the truth will out anyways as the project grinds on, and it is only with a realistic view of the situation that the president can figure out what choices to make.

Cheers,
Ben

PS There is a reason I don't talk to clients. :-)