David Cameron faces a showdown with his MPs over a referendum on the Lisbon Treaty, in a sign that old wounds over Europe are reopening in the run-up to a general election.
Amid indications that Ireland will vote "yes" in a national vote on the treaty this Friday, Tory MPs on the right of the party are mobilising for an "ambush" of the leadership at the Conservative party conference in Manchester two days later.
By contrast, a "yes" vote would boost Tony Blair's hopes of becoming the first permanent president of the EU – an appointment created by the Lisbon Treaty.
Hardliners, including the controversial Tory MEP Daniel Hannan, want the Conservative leader to commit to a referendum on Lisbon under a Conservative government, regardless of whether the treaty is ratified across Europe before the election.
However, Mr Cameron and William Hague, the shadow Foreign Secretary, have refused to give ground, saying only that they will "not let matters rest" and that a referendum Bill is being prepared for after the election – expected in May – in the hope it has not been ratified by all countries.
If Ireland votes "no" on Friday, there is no longer a pressing issue for Mr Cameron – but the latest poll put the "yes" camp far ahead on 48 per cent compared with 33 per cent opposed. The result, expected on Saturday, could overshadow the Tory conference at a time when Mr Cameron is capitalising on Gordon Brown's unpopularity.
There were signs last night of a "third-way" solution to Mr Cameron's problems. A compromise has been proposed by the Eurosceptic campaign group Open Europe for an alternative referendum on reform of the EU, even if the Lisbon Treaty is ratified. Yet this is unlikely to satisfy right-wingers in the party, who helped Mr Cameron win the Conservative leadership four years ago and still exert pressure on him.
Mr Hannan is to push the case at an Open Europe fringe meeting in Manchester, alongside shadow Europe minister Mark Francois.
In an interview with The Daily Telegraph yesterday, Mr Hague said there would be no announcement in Manchester. He said: "We hope we will come to a general election with the treaty unratified, of course we do.
"The treaty has not been ratified by all 27 nations and in that situation a Conservative government elected at the next general election will hold, as an immediate priority, a referendum.
"I have asked the Foreign Office to have a referendum Bill ready immediately after the election." A referendum would be held "within a few months". "As we can only have one policy at a time, there will be no new announcement, no departure from that in Manchester, whatever the result of the Irish referendum."
After Ireland, only Poland and the Czech Republic have yet to ratify. There will be a European Council meeting at the end of next month, at which candidates for president – including Mr Blair – and a European foreign affairs chief will be discussed. If the treaty has been passed across the EU, a further meeting in December could approve the appointments.
Last year, Ireland voted "no" to Lisbon, but the government provoked anger by announcing that it would put the question again. However, the economic downturn has allowed premier Brian Cowen to claim that Ireland's chances of recovery will be boosted as a fully engaged member of the EU. The "yes" campaign is said to have outspent the "no" campaign by €10 to €1.
Lorraine Mullally of Open Europe said that, given a "yes" result was predicted, "all eyes will be on the Conservatives and what they are going to do about it.... There is a strong public desire to be consulted on Europe one way or another," she said.
"So if Cameron doesn't promise a referendum on Lisbon he should hold a vote on an EU reform package, promising to veto EU budget negotiations if he doesn't get his way. The Conservatives should be wasting no time and already be thinking carefully about what will go in that reform package."