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.
How the No campaign twisted Clegg's words
It was the statement that returned to haunt Nick Clegg: in an interview with The Independent just over a year ago, he dismissed the alternative vote as a "miserable little compromise". The No campaign has dug out that quote again and again this year.
Mr Clegg insists his comment is being played back out of context – and he is right. The interview took place after the first TV debate between the leaders, which sparked "Cleggmania" and propelled the Liberal Democrats into second place behind the Conservatives in the polls. He said in the interview: "We are going for broke." So it was consistent with that to reject the minimalist electoral reform offered in Labour's election manifesto – a referendum on AV in 2011, seen as a last-minute gambit by Gordon Brown to enable him to retain power with Liberal Democratic support in the event of a hung parliament. Mr Clegg demanded "AV-plus", which unlike AV is proportional.
Mr Clegg actually said in the interview: "AV is a baby step in the right direction – only because nothing can be worse than the status quo. If we want to change British politics once and for all, we have got to have a quite simple system in which everyone's votes count. We think AV-plus is a feasible way to proceed.
"The Labour Party assumes that changes to the electoral system are like crumbs for the Liberal Democrats from the Labour table. I am not going to settle for a miserable little compromise thrashed out by the Labour Party." This explains why we today hold a referendum on a system that is not the first choice of any of the three main parties.
Reasons to vote Yes... readers opt for change
Hugh Thomas, 19, Wilmslow, south Manchester
"I think the system needs a shake-up. If it doesn't happen now then it won't for a long time."
Denise Wiand, 66, London
"I know people are saying that it is complicated but it is not complicated at all. You just rank the candidates."
Peters Ofomola, 46, London
"We are scared of change but AV is better so we should do it."
Martha Harron, 59, London
"There is so much scaremongering against AV that it makes me want to vote Yes even more."
Charlie Norfolk, 46, London
"I have lived in countries that are not first past the post, and it is a far fairer system."
Arnie Craven, 22, Pontefract, West Yorkshire
"Reform should be about finding ways of making our democracy work better."
Nana Osei, 18, Clapham, London
"I am voting Yes because it is fairer. People are saying it is expensive but sometimes we have to pay a bit more to get a fairer system."
Liz Ayers, Chiswick, London
"It is important that people really get their vote heard. It is not about one group of people getting what they want."
Ismail Mulla, 20, Dewsbury, West Yorkshire
"At the last election the Lib Dems increased their vote by one million but lost five seats. That seems unfair."
Barry Blatt, 43, Leeds
"In this country we have extremely disproportional representation."
More reasons to vote Yes... they're voting No
Nick Griffin, 52, BNP leader, Welshpool
"AV is designed to ensure permanent left-liberal government and is aimed at stopping the British National Party."
Peter Stringfellow, 71, nightclub owner, London/Majorca
"[FPTP] has worked well. [AV] is lazy voting... the smaller parties can hold the larger parties to ransom."
James Cracknell, 39, former Olympic rowing champion, London
"AV would be a disaster... AV is like an each-way bet: you can back everybody but the rewards are never as high."
Lord Tebbit, 80, former Conservative chairman, Enfield
"Disputed election results have until now been the exclusive preserve of the Third World."
Darren Gough, 41, former England cricketer, Milton Keynes
"When I was given out [in cricket], I had to walk. You didn't get a second chance, why should it be different in politics?"
Timeline: road to reform?
7am: Polls open for elections for English councils, the Scottish and Welsh parliaments and the AV referendum.
10pm: Polls close.
12.15am: Sunderland expected to be the first local council to declare.
1am: First results of the Welsh elections begin to come in.
2-3am: The majority of councils will declare their results, including big cities like Sheffield. First result in Scottish parliamentary election expected.
2-3pm: All Scottish and Welsh election results expected to be declared.
4pm: Counting starts in AV referendum. Regional results will be sent to the ExCel centre in London as they are declared.
7pm: Final result of AV referendum.
If there is a Yes vote today, the AV vote will be introduced for the next UK parliamentary elections, scheduled to be held in May 2015.