By Nick Assinder BBC News Online political correspondent

Blair is trying to hobble Brown

Well somebody should have told the chancellor.

Because Mr Brown has just ratcheted all the speculation onto another level.

By confirming he wanted a seat on Labour's ruling executive committee and that Tony Blair blocked him, he has unexpectedly brought into the open the disagreement between the two men.

Politicians almost never admit to rows in public, so for Mr Brown to admit this setback is extraordinary.

And the question on most Labour MPs' lips now is - for how much longer can this be allowed go on?

At odds

If anything is blahtastic, it is the increasingly hollow-sounding attempts to suggest these two men are best pals and that their relationship is one of the "great strengths of this government".

Frankly, many Labour MPs fear their relationship is more like the greatest weakness of the government.

It is certainly becoming the defining issue of the second-term New Labour administration and is threatening to dominate any third term.

Brown appeals to Labour grassroots

The two men are, it seems, at odds over a series of policies, most publicly on Europe and the euro.

And if the chancellor's resentment continues to smoulder and the prime minister continues to chop at him without finishing him off, the more chance this will do the government serious damage.

We have seen before what happens when chancellors and prime ministers fall out - just think of the most recent example of Margaret Thatcher and Nigel Lawson.

Sooner or later, something has to give. And history suggests it is usually the chancellor, although the prime minister inevitably suffers structural damage.

Tory chaos

Gordon Brown must think something different.

His supporters seem to believe that the prime minister's personal standing in the country and, more importantly for them, within the Labour party, has been dangerously, possibly fatally undermined.

The rows over policy and the war on Iraq have certainly landed Mr Blair in his most difficult period since he was elected leader.

Only the chaos in the Tory party has managed to shift the focus away from the turmoil in the Labour party.

But that looks like it has come to an end and the Tories, under Michael Howard, are ready to go for Labour's throat.

If the new opposition leader fails to make hay with this affair, he is not the man most believe him to be.

Power base

So attention is about to turn back onto the government and its troubles.

By popular consent, Gordon Brown's speech at the recent Labour conference was a clear attempt to set out his leadership credentials.

It fell short of a challenge and was more like a reminder to the party that he was still there, still Labour - emphatically not New - and that he was still waiting to inherit the crown.

The prime minister is clearly worried about his troublesome Chancellor and is moving to limit his power base.

He must be calculating that, if MPs and the wider grassroots party come to believe Mr Blair is becoming an electoral liability they will not hesitate to move on him, knowing there is a ready-made leader in the wings.

But there is little sign the splits in the party have reached that level, yet. And in any case, thanks to Labour's rules, removing an unwilling prime minister is hugely difficult.

It is certainly the case that, post-Iraq, Mr Blair's leadership is a matter of gossip and speculation around Westminster like never before.

Instead of the war making him even more powerful, it has weakened his position and alienated him from huge swathes of his own part and the public.

The prime minister is clearly worried about his troublesome chancellor and is moving to limit his power base.

The old whispers about him preparing to sack Mr Brown have even returned.

But that is the sort of high-risk gamble only a prime minister at the height of his powers and popularity can countenance - for Tony Blair, it may already be too late.

So, now this is all in the open, how will it all end? Almost certainly in tears.

Whether it will be Gordon Brown or Tony Blair who ends up weeping is still the biggest question in British politics.