By Nick Assinder Political correspondent, BBC News website

Tony Blair will be expected to take a lead

Tony Blair can never admit it publicly, but he will be hugely relieved that France has got him off a hook by voting "No" to the EU constitution.

He may well now be spared a leadership-threatening vote on the treaty in the UK and will avoid the months of division that would ignite.

But, even as he will be heaving that sigh of relief, he will be coming to terms with the fact that it will probably now fall to him to sort out the EU mess when he takes over the rotating presidency on 1 July.

There is even speculation that far from securing his leadership, the French vote may actually further weaken it.

But first the relief will come from the near certainty that, with the Dutch also likely to vote "No" on Wednesday and irrespective of what Mr Chirac urges, the constitution will now be sent back to the drawing board, or maybe even the mortuary.

There has always been the widespread belief that if France rejected the treaty, it would be pointless for the EU to attempt to press ahead with it, even if other countries supported it.

It may even be months or years before EU leaders map a new way forward

And that means, as the prime minister has previously signalled, there will be no referendum in Britain. You can't have a vote on something that no longer exists.

The last rites may not be uttered immediately, and there may even be attempts to find a way of reviving this treaty, perhaps at the EU summit next month.

But nothing dramatic is likely to happen in the immediate future and it may even be months or years before EU leaders map a new way forward.

So, without a UK vote, the prime minister will not be pitched into a long, bitter campaign aimed at turning around British public opinion which is currently overwhelmingly against the constitution.

Substantial downside

Had he lost that vote he would have been forced to resign as prime minister and would also have faced angry claims from his EU allies that it was Britain that had torpedoed the project.

Alternatively, it has been suggested that had he gone on to win the referendum, he would have then left Downing Street on a high.

But along with the relief that the worst has been avoided comes the downside - and it is pretty substantial.

Domestically it is certain to give new heart to the Eurosceptics

Apart from anything else, there is the straightforward damage that has been done to the entire EU project by this vote.

The prime minister is an enthusiastic European and will be disappointed by this result and the consequences for the EU.

Domestically it is certain to give new heart to the Eurosceptics, including the Tory party, who will seize on it to claim one of the most significant electorates within the EU have declared enough is enough.

Similarly, if there is no referendum in Britain, that may head off any eruption of the old Euro splits within the Tory party which did it such damage in the past.

But the problems are intensified for the prime minister by the fact that he takes over the EU presidency in July and will be expected to be in the lead in mapping out a way out of the crisis.

Lethal referendum

And all of this will come as his leadership is already under intensive scrutiny.

While the "No" vote in France may have averted a potentially lethal referendum, there are those in the Labour party who believe there is now no reason for Gordon Brown to hold back from taking over the leadership.

The chancellor, they claim, had been happy for the prime minister to take the lead, and all the flak, in a potentially damaging referendum campaign.

If there is to be no campaign, there is nothing in his way, they argue.

For now, however, there is likely to be a period of reflection as EU leaders mull over the consequences of this vote.

And for Tony Blair, those consequences remain unpredictable.