Nick Clegg: Coalition will survive even if voting reform Bill is defeated

In a surprise move that gave succour to Tory rebels opposed to the plans for an AV referendum, Mr Clegg said that the Coalition would survive even if the Liberal Democrat-backed legislation fell.

He told MPs: "The persistence and resilience of this coalition is not dependent on any one single piece of legislation."

His comments are sure to be seized on by rebel MPs who have so far remained loyal following threats from the whips that their opposition could topple the entire Government.

Lib-Dem MPs would also put huge pressure on Mr Clegg to quit the Coalition if he failed to secure their cherished ambition for electoral reform.

Signs of divisions re-emerged, with Tory MPs lining up at Prime Minister's Questions to hit out at proposals to hold the referendum on May 5 next year.

There is concern over plans to hold the plebiscite on the same day as voters in Scotland, Wales and Northern Ireland elect members of their devolved legislatures. Already, 43 have signed a Commons motion calling for the date to be changed because of fears the vote could effectively be skewed.

Tory backbencher Eleanor Laing asked Mr Clegg how he could "justify" the £100 million cost of the referendum when families and businesses were facing tough economic times.

Fellow Conservative Christopher Chope asked him if the Liberal Democrats would leave the Coalition if they failed to get legislation paving the way for a referendum on the Alternative Vote through Parliament.

Mr Clegg told him: "This Bill is only one part of a much, much wider programme of political reform, including giving people the power of recall ... to clean up party funding, to produce proposals finally to reform the House of Lords. Political reform doesn't begin or end with this one single Bill."

The plan is contained in the Parliamentary Voting System and Constituencies Bill, which gained its second reading in the Commons on Monday, although 10 Tories rebelled.