By Nick Assinder BBC News Online political correspondent

Decision day on the euro is imminent

If there is one thing Tony Blair is never short of it's advice on the euro.

He has the Liberal Democrats along with one section of business, the unions and his own party telling him to get a move on and join.

And he has an equally vocal group, often from the same sections of society, and led by the Tories - most of them anyway - urging precisely the opposite.

But with this historic decision now within spitting distance it appears Tony Blair is in open warfare with the one man whose advice he should be absolutely relying on - his Chancellor.

Gordon Brown is still going around letting it be known through "friends" that there is no way he will countenance a referendum on the euro this side of the next general election.

Indeed, he uses every platform available to him to rubbish other EU economies and stress what a wonderful job he has done of transforming the British economy.

Five tests

The clear message is that joining the euro can only be at best risky and at worst disastrous for the domestic economy.

And it appears he is about to produce a book-sized document setting out precisely whether or not his famous five tests have been met.

What is dismaying many on both sides of the argument is that the two men responsible for this momentous decision still haven't agreed on their course.

It is likely the conclusion will be far from a resounding "yes". Indeed, the old suspicions that the tests were designed precisely not to give a definitive answer but allow a political one have never appeared more accurate.

Meanwhile, the prime minister's camp are equally active in telling anyone who will listen that any decision to delay a referendum will be temporary - it could still be held this side of the next general election.

The prime minister's hit man, Commons leader John Reid, has made that crystal clear. A decision next month would be "for the time being."

And, as all this wrangling is going on, it has emerged there has been no cabinet discussion on the issue at all.

The assumption amongst ministers is that they will be informed rather than consulted when the time comes. But that time is virtually here.

Winning the war

And what is dismaying many on both sides of the argument is that the two men responsible for this momentous decision still haven't agreed on their course.

It is pretty astonishing that, with just three weeks or so before the government meets its self-imposed decision deadline, there appears to be open disagreement at the top.

Once the undergrowth of claims, counter claims and spin is chopped away, however, one thing does emerge.

Precisely how the prime minister will rid himself of his troublesome anti-euro priest is set to become the greatest political soap opera of the age

It looks pretty certain that the Chancellor has won the battle, if not the war.

He is almost certainly about to announce that the five tests have not yet been met and that it would not be in Britain's interests to join the euro now.

But he may have to hang back from ruling it out at any time before the next general election.

Shift for Brown?

That would leave the door open to a referendum at some future point over the next two years.

Now that begs another fascinating question. If Tony Blair wants a vote before the general election, what will he do about Gordon Brown, who shows no sign he is about to change his mind any time soon.

Some are whispering in his ear that he should exile the chancellor to the Foreign Office.

But the idea that Mr Brown would accept such a move, or keep quiet even if he did, does not seem likely. And sacking him would be suicidal.

So precisely how the prime minister will rid himself of his troublesome anti-euro priest is set to become the greatest political soap opera of the age.