By Andrew Marr BBC political editor

All the way through this crisis we've been saying two things.

First, that the really dangerous moment for Britain would come if the United Nations and the rest of the Security Council were going in one direction over the inspections and America went in the other.

We are much closer to that tonight, that's what really seems to be happening.

And second, we've been saying that at that moment, we thought Britain would go with America.

The heat is on Tony Blair

That is very clearly the case tonight.

The British signs and statements coming out are very much more like the American ones in tone.

Deep, deep scepticism about this Iraqi offer.

It's not enough to simply say you can't come in without prior notice to these palace complexes, these enormous areas, because that is where Britain and America and other countries believe a lot of these things are hidden.

So, it's already looking like there is some kind of division at the top of the United Nations and that Britain and America are standing together - the dangerous moment.

It's an intensely difficult diplomatic dance

Mr Blair has one not-so-secret weapon, Bill Clinton.

There is a seething scene of Clinton-mania going on in the hotel where the former president has just been addressing a Labour Party dinner.

He urged people to stand shoulder to shoulder with America, saying it's very, very important.

He doesn't go along with President Bush on lots of things but on this he says it's absolutely essential that Tony Blair carries on standing alongside him.

And he'll be giving the same message to the conference on Wednesday.

Tony Blair is also talking privately with Bill Clinton because he has to read what's going on in the American administration.

This has all been about, from the British point of view, insuring those people in the American administration determined to go to war at all costs were reined in and those willing to work within the United Nations were encouraged.

That's the game he has to play.

It's an intensely difficult diplomatic dance.