Leading article: Mr Cameron has backed into a corner over Europe

From the last week's rising chorus of legal queries and political caveats, it would be easy to conclude that the latest effort to patch up the eurozone is falling apart before it has even come together. Better still, for David Cameron, would be the verdict that other countries' post-agreement equivocations vindicate his decision to veto the proposal.

Neither is the case. Indeed, now, more than ever, the Prime Minister should be working to undo the damage of his isolationist position.

That said, there are certainly causes for concern about the latest, hesitant step towards a resolution of the crisis in Europe. The eurozone is still teetering on the edge of a precipice: French broadsides against the British economy only emphasise fears in Paris about the almost-certain downgrade of its triple-A credit rating; Italy needs to refinance a terrifying €320bn public debt next year; economic conditions continue to deteriorate.

Meanwhile, the political and legal challenges facing the eurozone's proposed "fiscal compact" are of awesome proportions; plans for an accompanying financial backstop are alarmingly absent and the overexposure of European banks remains unaddressed. Even so, it is premature to dismiss the scheme as unworkable, and entirely wrong to conclude that Mr Cameron was right to pull Britain out of it.

While yesterday's draft agreement from Brussels makes progress on several contentious issues, further reservations will no doubt surface over the coming weeks. But none automatically means failure. It is only to be expected that individual countries press their own priorities and consider their own domestic politics. How could they not? Concern that all the necessary accommodations cannot be reached within the timescale demanded by the nervy bond markets is one thing. Concluding that such hesitations leave Britain less isolated than it first appeared is quite another.

Mr Cameron's supporters might perhaps claim British involvement in talks on the new pact as evidence that his strategy was an effective one and nothing of note had been lost. Indeed, Downing Street was yesterday stressing the fact that British officials will be "equal participants" in all negotiations. Hardly. Our officials may be at the table, but they do not have a vote. Nor does the UK have any remaining political capital. Despite the remarkably conciliatory tone from Germany this week (in stark contrast to the defensive economic posturing of the French), Mr Cameron's cack-handed diplomacy has sadly confirmed the European view of the UK as recalcitrant, unconstructive and oversensitive to the Tory right.

There is still time. But, as the negotiations move ahead, Mr Cameron will have to prove himself willing to compromise, rather than pursuing his unedifying tactic of trying to rustle up support for his "No" from countries that may have their own doubts. Nor will deputing the arch-Europhile Nick Clegg to use his extensive contacts to smooth things over be enough. The move may seem sensible as an attempt to soothe outraged Liberal Democrat sensibilities, but it will do little for Britain in Europe. The Deputy Prime Minister's credibility was irretrievably undermined by Mr Cameron's pre-dawn phone call informing him of the veto as a fait accompli. More important still, it was Mr Cameron who slammed the door, and only he can open it.

There's the rub. Since last week, the Prime Minister has been riding high on the adulation of his Eurosceptic backbenchers. But he has backed himself into a corner. Any hint of a deal with Europe will be seen as a U-turn, but realpolitik demands a more nuanced approach. The current mixed messages cannot continue. Nor can the neutered Mr Clegg do it alone.