Forty million people will get the chance to support an historic change to the British voting system today.
"Super Thursday" will see the UK's first nationwide referendum for 36 years, as well as the customary elections to English local authorities, the Scottish Parliament, the Welsh Assembly and Northern Ireland's Assembly and councils.
Yesterday the three leaders of the main Westminster political parties made their final pitches to voters. The stakes are high for all three men.
Nick Clegg anxiously awaits the public's verdict on his party's long-cherished goal to scrap the first-past-the-post system – and braces for the loss of hundreds of council seats.
He will cast his referendum Yes vote and town hall vote in his Sheffield Hallam constituency, where the Liberal Democrats may struggle to hold on to power on the city council. In line with tradition, he will not campaign today.
David Cameron, facing his first major test of public opinion since becoming Prime Minister, and following the Conservatives' failure to win an outright majority in last year's general election, will cast his ballot against the alternative vote in London before returning to Downing Street. He, too, faces the loss of hundreds of town hall seats but will be cautiously optimistic about the referendum result after the final opinion polls put the No lobby well ahead.
Ed Miliband, who has already cast a postal ballot in his Doncaster North constituency (Yes to AV), will hold meetings with his advisers in his Commons office. He is hopeful of gaining 600 council seats in his first electoral test but experts say Labour should gain 1,000 to show it is making progress. And he faces a setback in Scotland, where Alex Salmond's Scottish National Party may scupper Labour's hopes of regaining power.
Last night Mr Miliband insisted that the AV referendum was still winnable. "There is still time for people to make up their minds," he said."There is still time for people to focus on the issue."
The Labour leader again urged the public not to use the plebiscite to give Mr Clegg a bloody nose for joining the Conservatives in coalition. "This is not about a particular individual. It is about a big change, a once-in-a-generation chance to change politics. In the 10 minutes it takes to vote, you could help change British politics for the better."
The Labour leader warned that if a No verdict is returned when the votes are counted tomorrow, electoral reform would be off the agenda for a long time. "I don't think we are going to be coming back to this very quickly," he said. "I do think there is an anti-Conservative majority in this country and I don't think first past the post gives expression to it."
Mr Clegg, too, refused to concede that the referendum was lost, saying many people would not turn their minds to how they would vote until today. "If you basically think the current system is absolutely fine, totally perfect, nothing wrong with it then obviously vote No and stick with what we've got," Mr Clegg said. "If you want something a bit fairer, a bit better, which makes all politicians work a bit harder for your vote then vote Yes, vote for change."
Two new surveys were broadly in line with yesterday's ComRes poll for The Independent showing that 66 per cent of people certain to vote would back the No lobby and 34 per cent the Yes camp. A poll by research agency TNS produced exactly the same figures while an ICM survey for today's Guardian suggested 68 per cent would vote No and 32 per cent Yes.
A YouGov poll for The Sun pointed to a closer result, with the No camp on 60 per cent and Yes on 40 per cent.
In the Commons, the Prime Minister defended the current system after Bob Russell, the Liberal Democrat MP for Colchester, told him it produced results "that would embarrass Robert Mugabe". He added that, at last year's general election, the Tories polled 49 per cent of the votes in Essex but won 95 per cent of the seats.
Mr Cameron replied that, despite the differences between the Tories and Liberal Democrats over AV, there was "as good an argument" today for the Coalition as when it was formed. "Of course we do not agree about the future of our electoral system. We are having a referendum, we are having a debate about it," he told MPs.