The question of Iraq will expose all Mr Blair's skill – and his vulnerability

How can he manage the debate when President Bush cannot even control the statements of those at the top of his administration?

Before the 1997 election, Roy Jenkins conjured up a vivid metaphor. As Labour nervously sought power for the first time in 18 years, he said that Mr Blair was carrying a fragile vase across a crowded room, acutely aware that any misplaced twitch or gesture and the object would smash into a thousand pieces.

The metaphor came to mind on Tuesday afternoon during Mr Blair's press conference dominated by Iraq. He was articulate, resolute and in command, yet uttered virtually nothing new. He could not say much of substance because there was not much more of substance to say. He could not give a hint of weakness or else Saddam would sense further disarray. At the same time he needed to make a nod of sorts to show that he recognised the worries of the doubters. Mr Blair had got hold of another fragile vase and was starting to cross a crowed room again.

In spite of yesterday's dramatic headlines, Mr Blair has stated many times, at Prime Minister's Questions, in interviews, during other press conferences, that the issue of Iraq's lethal weaponry had to be addressed. He has also been deliberately vague for months about the possibility of a new UN resolution. On Tuesday Mr Blair made a familiar point, but with a fresh and cunning linguistic contortion. He told the assorted journalists that "The UN has to be a route to deal with this problem, not a way of people avoiding this problem." The tone was internationalist, yet the approximate translation of these words is: "The UN matters, but only if it agrees with our point of view."

In a minor key the contortion reminds me of what Mr Blair once said as Leader of the Opposition, on the verge of becoming Prime Minister, to a local government conference. He told his excited audience that "A Labour government would give more freedom to councils as long as they exercised that freedom responsibly." In other words councils could do what they wanted as long as it was what a Labour government wanted them to do.

Indeed there are many echoes now from Mr Blair's approach to domestic politics in his early years as Labour leader. Before winning the 1997 election he adopted a similar clarity of tone, quite often disguising imprecision in terms of policy. He told me in an interview in July 1996: "We believe in modernising the welfare state – precisely how we do it is a matter for government, but be in no doubt that we will." Famously he declaimed that "Education is our number one priority." Yes, but how were improvements going to be implemented? They were less clear at the time.

There were good reasons for the evasiveness then. There is no point in an opposition party outlining potentially unpopular polices. The combination of radical intent, clarity of tone and evasiveness made Mr Blair the most formidable opposition leader since the war.

The big difference is that on the domestic front he was in complete control of the pace, deciding when evasive arguments became more substantial policy developments. He has remained in control ever since, his only obstacle being the Chancellor – and on most issues Mr Blair and Gordon Brown have similar instincts. They decide when a vague pledge to "modernise" the welfare state becomes something more specific, or not as the case may be. They decide when to review the economic tests for a single currency.

But on Iraq, Mr Blair is not in control of the pace. He does not decide alone when evasive arguments become more substantial, when those more substantial arguments translate into action. That is why the most evasive and misleading word deployed in his press conference last Tuesday consisted of two single letters. The tiny word that disguised a thousand risks and problems was "we".

"Whatever timelines we have been working on, the debate has moved on... Where we are in absolute agreement is that Iraq poses a real and unique threat... we have to face up to it and deal with it."

That tiny word "we" evokes a sense of community, a collective sense of purpose. Yet currently most British voters, many ministers, Labour MPs, the rest of the European Union and nearly all Saddam's neighbours in the Middle East, terrified of the destabilising impact of a war in Iraq, are not part of the "we". The word is misplaced even if it is taken to mean Mr Blair and the US, as the Bush administration is openly divided over the issue. How can Mr Blair manage the debate when President Bush cannot even control the public statements of those at the top of his administration?

In terms of the public debate, this is what makes the current situation so much more hazardous than Kosovo and Afghanistan. In the case of Kosovo, Mr Blair genuinely set the pace, galvanising President Clinton, who was characteristically divided within himself – an easier division to deal with than public splits at the top of an entire administration. Over Afghanistan there was a spontaneous unity.

It is just about possible to discern a way through all of this from Mr Blair's perspective. Judging by the hesitant, bumbling performance of the Foreign Office Minister, Mike O'Brien, on yesterday's Today programme, the path is unlikely to be cleared by the publication of the dossier showing the evidence of Saddam's lethal weaponry. Mr O'Brien did not sound especially enthused, and he has seen the dossier. My understanding is that the document will largely contain evidence that is already public knowledge, inevitably dated and speculative as weapons inspectors have not been carrying out their work for four years. This document is starting to acquire an aura because of its absence rather than for what is likely to be in it.

Mr Blair is right to highlight instead the ambiguous findings of the opinion polls and the statements from senior dissidents in his own ranks. Most of them do not rule out force. What they seek is evidence that Saddam is a threat, that the international community and international law matter. What they oppose with good cause is a US strike backed by Britain, or rather the British Prime Minister, with the dominant partner indifferent to the wider international community and international law. As far as Mr Blair has a role, it is to put pressure on President Bush to take – and be seen to be taking – all possible steps to carry wider international opinion. A start would be made by refocusing the debate on the weapons inspectors rather than on the imminence of war.

It does not require the services of a psychiatrist to explain Mr Blair's position. On Tuesday he said he supported the US on Iraq because he agreed with its stance on Iraq, not out of blind loyalty or delusions of grandeur. On this I am sure he was speaking the unambiguous truth. For sincere motives he has chosen to carry a vase across a room full of traps over which he has little control. There is a much greater chance of the vase smashing to a thousand pieces than was ever the case when Mr Blair smoothly crossed a crowded room to win the 1997 election.

s.richards@independent.co.uk