There could be a free vote in Parliament on any new European constitution

The relentless demand for a referendum from papers such as 'The Sun' cannot fail to take its toll in the long run-up to a general election

Conventional wisdom has it that the New Year is the decisive moment for the Blair premiership. Lord Hutton's report in the middle of January, to be followed perhaps a couple of weeks later by the vital parliamentary vote on top-up fees, combine, it's assumed, to make next month the one which will decide whether or not he goes on to fight a third general election as party leader.

It may not be quite as simple as that. Of course a defeat in the second reading of the Higher Education Bill, as Blair himself was almost eager to imply last week, would be a severe, and perhaps fatal, blow to his authority. But while his troubles would no doubt be eased with a Commons victory on fees, they would hardly disappear overnight. The Bill still has a long way to go after that, not least in the Lords, which could well amend it within an inch of its life, as it chose to amend the Bill introducing foundation hospitals. And that could leave open the question of whether the Commons might have another cliff-hanger vote much later in the year on whether to approve them, as they did on foundation hospitals.

There's another reason, moreover, why even surviving January may not mark the beginning of a free ride for the Prime Minister up to the next general election. A reason which by next week could well become a great deal more apparent than it is now. Which is the press and opposition chorus - so far doing little more than waiting in the wings softly rehearsing its tunes - that will demand a referendum on the outcome, assuming there is one, of this weekend's Intergovernmental Conference in Brussels on a new EU constitution.

This is not in the same category as top-up fees, of course. His unelected tormentors cannot inflict the same kind of damage as the Commons itself. But it's possible that the House of Lords will add to the agony by passing an amendment calling for a referendum. Indeed the chances of it not doing so depend on the scale of a likely split among the pivotal Liberal Democrat peers, who will be theoretically bound by the party's policy in favour of a referendum, but a section of whom are ardent pro-Europeans who followed the late Lord Jenkins of Hillhead into the Social Democratic Party. Even if the Lords don't finally back it, the relentless demand for a referendum from papers such as The Sun cannot fail to take its toll in the long run-up to a general election.

The Fabian paper published yesterday by Gisela Stuart, the former Labour minister who sat on the convention under Valery Giscard D'Estaing which produced the draft treaty, can hardly fail to fuel that demand, as The Sun was quick to see, treating the paper's doubts and fruity criticisms of the undoubtedly elitist drafting process to a full two-page spread. Ms Stuart underpinned her emphatic assertion that the British Government did not have to accept the treaty with an ominous warning in a newspaper article that the real reason for having a constitution was "a political deepening of the union".

While Ms Stuart balanced her criticisms with a proclamation that she needed no convincing that Europe "has been a force for good" and support for the "red lines" set by the Government in its negotiations, there was plenty in her paper for the Conservatives and their cheerleaders to seize on in the arguments ahead.

It's likely - though not yet certain - that the Government will achieve a treaty in conformity with those red lines on tax, defence and foreign policy this weekend. Britain is far from alone in disliking the far reaching proposals from the Italian presidency for majority voting on foreign and security issues. The neuralgic clause on tax fraud and evasion could be tightened to deal with a key objection by the treasury, fearful that it could be a back door to tax harmonisation: although any country can veto a decision to deal with an abuse by majority voting, the British would ideally like the veto made immune from legal challenge in the European Court. And so on. But that won't stop the clamour for a referendum, as Ms Stuart rightly asserts.

There is much of interest in her paper. Her irritation with Peter Hain's unguarded description of the new constitution as a mere "tidying up exercise" is certainly justified. Assuming that the UK does not give way on its most publicised red lines, there will still be a real shift of sovereignty, for example on other issues such as asylum and immigration. But as Ms Stuart herself acknowledges, that is strongly in British interests because it increases the EU's responsibility to mount effective controls at its external borders.

The principled case against referendums in a representative democracy is very powerful, because they undermine the strength of the representatives and the importance of the elections that put them there if they are too often bypassed when issues of controversy arise. It is a pity that the present Government has partly contaminated that case by the relative frequency with which it has called referendums on everything from Welsh devolution to elected mayors.

But that still leaves intact the argument that the New Treaty isn't remotely in the big league - say - of the euro, or the 1975 decision to go into the European Common Market. Indeed it pools no more sovereignty, and arguably a good deal less, than the Single European Act which ushered in the single market and which Margaret Thatcher did not dream of putting to a referendum.

Indeed Ms Stuart's frustration that the convention didn't do more to take powers off the EU and restore them to the nation state underestimates the extent, central to Mrs Thatcher's Act, that a supranational authority, with increasingly detailed responsibilities, is needed to enforce the single market. What's more she - oddly - does scant justice to her own success in securing an entirely new "yellow card" clause under which national parliaments can block EU decisions that they regard as more appropriate to be dealt with by the member states than by the union.

Yet for all the damage she has done, unwittingly or not, to the Government's case against a referendum, there is one idea of real significance in her paper. Which is that if there is not to be a referendum, a free vote in Parliament might be an alternative. The Government will not rush to welcome this. But it would be unwise to rule it out altogether.

The probability is that it would win a Commons vote, especially if it insisted that ministers had to vote yes to the Treaty if they wanted to stay in the Government. A significant minority of Tories might vote with them. But a free vote would ease some of the pressure for a referendum while enhancing, rather than undermining, parliamentary democracy. The Government is right to resist the clamour for a referendum. But a Prime Minister with an increasing tendency to gamble might well judge that a free vote was the best bet for facing down the torments on Europe that now await him.

d.macintyre@independent.co.uk