Maastricht ratification faces fresh onslaught: Labour's Commons move could threaten Major's future as Prime Minister

A STRONG all-party threat to block ratification of the Maastricht treaty opened up in the Commons last night.

Michael Morris, chairman of the committee stage examination of the European Communities (Amendment) Bill, agreed to allow further debate on the controversial social chapter opt-out - and offered a vote on a Labour new clause that could attract the support of a Commons majority.

George Robertson, Labour spokesman on Europe, said the new clause was a 'killer amendment' to the Bill, and amounted to a 'ticking bomb' under ratification. Some senior Labour and Tory sources went further, saying that if ratification was stopped, John Major's future as Prime Minister could be in doubt.

With disaffected Tories talking of a possible leadership challenge against Mr Major in November, parliamentary rejection of Maastricht ratification could force his resignation. Douglas Hurd, Foreign Secretary, has emerged as front-runner for the succession - with surprising backing from some senior Thatcherites.

Meanwhile, the focus of immediate Westminster speculation was on New Clause 75, chosen by Mr Morris as the vehicle for opposition attack on the ratification process. Sponsored by the Labour backbenchers Stephen Byers and Geoff Hoon, the new clause would add a further obstacle to ratification of the treaty.

It proposed that after the Bill had been enacted by Royal Assent, the treaty could not be ratified until the Commons had voted on a further, separate government motion 'relating to the incorporation or otherwise' of the UK into the social chapter.

The Government last night won a vote - with Liberal Democrat support - to continue debate on the Bill through to this morning, by 304 to 299, a majority of five. That decision will advance debate on New Clause 75, and the key vote, to the week after MPs return from the Easter break - beginning 19 April.

The new clause could be carried with the support of all Opposition parties and a hard-core of a dozen Tory rebels. Those same rebels could then threaten to defeat the ratification trigger motion - unless Mr Major agreed to offer the referendum for which they have been campaigning.

While allowing debate on the new amendment, Mr Morris ruled out a separate vote on Amendment 27, deleting the social chapter opt-out from the Bill.

There were fears and suspicions, on both sides of the House, that there had been 'a stitch-up' between the Conservative, Labour and Liberal Democrat supporters of Maastricht; dumping Amendment 27 because it was the biggest threat to the treaty.

Critics were not immediately reassured by New Clause 75, and the Prime Minister's office said 'show-stoppers' had been promised before, but the show continued.

Mr Robertson said the new clause put the Government back on the hook it had slipped off after the Attorney General had advised the Commons that Amendment 27 would not halt ratification. If New Clause 75 offers the only chance of blocking ratification, it could well get the necessary support.