The campaign against reforming Britain's voting system will today claim that the change will cost taxpayers tens of millions of pounds which could be spent on public services.
Opponents of the proposal will also say that Nick Clegg, the Deputy Prime Minister, gave up on his pledge to protect students from higher fees as part of the coalition negotiations in order to "wring" the referendum vote out of the Conservatives.
Meanwhile, supporters of the Yes Campaign for Voting Reform will unveil two rather unlikely supporters of their crusade: King George VI and Queen Elizabeth. The actors Colin Firth and Helena Bonham Carter, who both won Baftas for their portrayal of the royal couple in The King's Speech, have sent messages of support to the "Yes" camp.
The Oscar-tipped Firth said: "The referendum is a once-in-a-generation opportunity to change our clapped- out politics for good. I'll be voting yes."
They will be joined by the comedian Eddie Izzard, Martin Bell, the former independent MP, and Greg Dyke, former Director-General of the BBC, who are to become vice-chairs.
The Yes Campaign has deliberately eschewed endorsements from politicians and hopes to capitalise on the unpopularity of Westminster politics to encourage voters to change the system.
Nick Clegg, a proponent of electoral reform, will take a back seat in the hope that the Yes Campaign does not get tarred with the unpopularity of the Liberal Democrats in Government.
The No Campaign will present the fertitlity expert Lord Winston as a backer at its launch today.
In November, the No Campaign announced Margaret Beckett as President and Vice-Presidents included David Blunkett, Lord Prescott, Lord Reid, Ken Clarke William Hague and Steve Norris.
The No Campaign has no intention of allowing Mr Clegg to take a back seat. At a press conference today they will claim that he put alternative voting (AV) ahead of other Liberal Democrat priorities such as student finance.
"He went into a room with the Tories, shut the door and decided that tuition fees were less important to him than PR," said a spokesman for the No Campaign.
"We have worked out exactly how much introducing AV will cost and I think the public will be quite shocked by it. This is money that could be spent on protecting public services from cuts."
A Yes Campaign spokesman said: "We know that they will come up with some nonsensical inflated figure for how much a fairer voting system will cost. But our belief is that democracy is a value not just a system."
On Sunday a ComRes Poll for The Independent on Sunday showed the "Yes" camp with a 10 per cent lead.
A Bill to ensure a May referendum is currently going through Parliament. It is being held up by Labour in the House of Lords but is expected to be passed by the deadline of Thursday when both houses recess for the half-term break. Government sources said they were prepared for both Houses to have to sit through the night in order to ensure the legislation was on the statue books in time.