Brown plans referendum on electoral reform ideas

Gordon Brown will attempt to rush through a law calling a referendum on changing the voting system within 18 months of the general election.

The Prime Minister will announce next week that the Government will table an amendment to the Constitutional Reform and Governance Bill, proposing a referendum on reform.

The public would be given a straight choice between retaining the first-past-the-post system and switching to the Australian alternative vote (AV) system, in which people can rank candidates in order of preference. The one who comes bottom drops out, and second preference votes are redistributed until one candidate has more than 50 per cent of those cast.

Although parliamentary time is short, the move could win approval - possibly during the horse-trading between the parties in which measures are rushed through once the election is called. The plan creates a dilemma for David Cameron. The Tories oppose change to the voting system, but he may not want to block a Bill which would also include reforms following the MPs' expenses controversy. If a referendum is enshrined in law, an incoming Conservative Government would have to pass new legislation to stop the plebiscite taking place.

The Liberal Democrats may amend Labour's proposal to make it proportional, in line with the "AV plus" system recommended by the late Lord Jenkins of Hillhead in 1998. But Labour is counting on Liberal Democrat support to secure approval in both the Commons and Lords. Jack Straw, the Justice Secretary, said last night that AV was the "radical" rather than "conservative" option on voting reform.

The Prime Minister is expected to announce the Government's decision in a speech after it has been formally rubber-stamped by the Cabinet next week. It has been supported by the Cabinet's Democratic Renewal Council, which is chaired by Mr Brown.