TONY BLAIR is facing the political isolation that all Prime Ministers eventually experience. He is running out of close and dependable allies. That is why the threats to John Prescott and Charles Clarke matter. They leave Mr Blair himself looking increasingly exposed.

Exactly the same happened to Baroness Thatcher in her third term, when, through ill-health and disagreements, she lost half a dozen close supporters and pillars of her Government. She was, therefore, very vulnerable to the revolt by Tory MPs and many of her Cabinet in November 1990.

Similarly, now, Mr Blair has lost strong Cabinet allies such as Peter Mandelson, Alan Milburn and David Blunkett. This year, Tessa Jowell, one of his closest supporters, and Ruth Kelly both faced serious difficulties, which they have survived, with bruises. But now Mr Clarke and Patricia Hewitt, two of the ablest ministers, are in serious difficulty. This leaves the ranks of the Blairites looking battered and depleted. He has few natural allies to whom he can turn.

Mr Prescott’s position is different. He has never been a Blairite, or new Labour. But, as Deputy Prime Minister, he has performed an invaluable role for Mr Blair as a bridge and a shield.

He has been Mr Blair’s link to traditional or old Labour, the party’s trade union and working-class roots. Despite doubts, he backed Mr Blair’s rewriting of Labour’s Clause Four statement of aims and values in 1994-95, and has since defended the Prime Minister in times of trouble.

Mr Blair has handled his deputy skilfully, recognising Mr Prescott’s lack of selfconfidence and hatred of being patronised. So Mr Blair has tolerated his prickliness as well as his weaknesses as a minister and his resistance to some Blairite ideas such as elected mayors. More recently, Mr Prescott has been the only senior minister able to mediate between Mr Blair and Gordon Brown as their relationship has become increasingly fraught. During times of tension, Mr Prescott has been able to talk to the two frankly, urging them to work together for the sake of the party. Mr Blair and Mr Brown have accepted Mr Prescott’s role as the guardian of the transition from the one to the other.

Yet Mr Prescott’s credibility in this role, and his selfesteem, have been shattered by all the publicity over his affair with his former diary secretary. It is no good saying that it is a private matter. The results are being played out in public. His authority has been undermined. Appearing like Falstaff does not go with the dignity of being Deputy Prime Minister.

Of course, Mr Blair has personal sympathy for the plight of Mr Prescott and his wife Pauline. That reflects a dozen years of working together. But Mr Blair’s regrets now go beyond the personal to the implications for his own political survival. Mr Prescott is no longer central, or even essential, to the handover to Mr Brown.

In the very short term, the priority for Mr Blair is to keep Mr Prescott and Mr Clarke in office until at least Thursday evening after the close of polls for the local elections. But, afterwards, while not wanting to lose either minister, he has to consider the damage their very different problems are causing the Government and him. For all his charm, Mr Blair is ruthless and willing to discard even close allies, as Mr Mandelson can testify.

Mr Blair’s calculation next weekend, after what look likely to be very bad results for Labour, is what will be necessary to secure his position and revive his Government over the next year or two.

The fate of Mr Prescott and Mr Clarke are bound up with the politics of survival — Mr Blair’s, not theirs.

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