Turning point for Blair and Brown?

By Nick Assinder BBC News Online political correspondent

Nick Brown's decision to switch sides and back the government's tuition fees policy is probably the turning point in the biggest ever threat to Tony Blair's leadership.

And it is being seen by some as a turning point in Chancellor Gordon Brown's ambitions to become the next Labour leader.

Brown is seen as part of Chancellor's camp

Once the rebel leader announced he had squeezed enough concessions out of the government to allow him to back the policy, the chances of the revolt failing immediately rose.

But at what cost to the policy the prime minister has described as a "flagship" measure and central to his crusade to reform the public services?

And, more importantly, what does it say about Chancellor Gordon Brown's intentions and Mr Blair's current standing within his party?

Because, whatever may be claimed, most of those in Westminster I have spoken to believe this about-face came on the direct orders of the chancellor.

Simple choice

Nick Brown has been widely accepted as being the chancellor's lieutenant in the Commons and had been engaged in a powerful whipping campaign to rally rebel votes against the policy.

He stated on many occasions that, as long as there was an element of variability in the policy, he could not support it.

Blair edges closer to victory

The latest concessions leave variability in the Bill, but also mean there will be a wide-ranging review of the system before it has even got off the ground.

Some will see this as a major sop to middle England and will claim it has, in effect, neutered the policy.

But this decision smacks of big, long term political manoeuvring.

As deputy prime minister John Prescott declared just hours before the vote, it had come down to a simple choice: "Do you support your Labour government or don't you". And for Labour government, read Tony Blair.

Low profile

If the rebels answered "no" to that question it would, he admitted, weaken the prime minister's position, particularly coming just a day before the publication of Lord Hutton's report into the death of Dr David Kelly.

Many on the Labour benches believe it would mark the beginning of the end for the prime minister who has invested his personal authority in victory.

Brown still wants top job

And, of course, it is still possible that may happen. It is just hugely unlikely.

The chancellor had kept a low profile as the rebellion grew - although it is important to reiterate that Nick Brown had been at great pains to distance himself from Gordon Brown when opposing this policy.

It has only been in the closing stages - with his GMTV interview on Sunday - that he has unequivocally taken the lead in the fight for top-up fees.

His interview led to speculation he had been offered a new pledge from Tony Blair that he was ready, at some point in the not-too-distant future, to hand him the reins of power.

Serious fallout

Monday's headlines were predictable, declaring the comment was the clearest sign that the two men had come to an understanding over the future leadership - probably at their kiss-and-make-up meeting at the end of last year.

Once the chancellor was reassured about his future leadership - and, coincidentally seen major concessions to the proposal - the dogs could be called off.

These speculations will be dismissed by all concerned.

But it will be difficult to persuade many in Westminster that this is not what this is all about.

And, in any case, the fact that the prime minister has apparently had to rely on Gordon Brown to deliver the troops itself speaks volumes about their relative power bases.

There will still be some pretty serious fallout from it all.

There are any number of backbenchers who will feel they have been let down by Nick Brown and others who will be furious at what they will see as a government stitch up.

And it is quite likely that Mr Blair's leadership will never be quite the same again.