Britain's opposition Labour Party leader Ed Miliband campaigns against Scottish independence in a shopping centre in Edinburgh, Scotland, September 16, 2014 (Photo: Reuters)
Campaigners for and against Scottish independence scrambled to win over voters on Wednesday on the final day of campaigning as fresh opinion polls suggested a very slight majority for the "No".
Both camps were planning rallies across Scotland on the eve of the historic referendum, with polls indicating there is still a large section of undecided voters who could swing it either way.
In a letter to the people of Scotland, pro-independence First Minister Alex Salmond urged the electorate to take its historic chance to end the 307-year-old union with England.
"Wake up on Friday morning to the first day of a better country. Wake up knowing you did this -- you made it happen," Salmond wrote.
"It's about taking your country's future into your hands. Don't let this opportunity slip through our fingers. Don't let them tell us we can't. Let's do this."
But Alistair Darling, a former British finance minister who heads up the "No" campaign, said there would be "faster, better change" for Scotland within the United Kingdom.
Britain's three main political parties have promised greater powers for the Scottish government in the event of a "No" vote.
"We have all built the UK together and we have benefited from that strength.
"I think it would be a tragedy if that relationship were broken," he told BBC radio.
All three polls published in newspapers on Sunday showed that support for independence had increased, but that when undecided voters were excluded, independence was set to be rejected by 52 percent to 48 percent.
The ICM poll for The Scotsman newspaper said "No" support was ahead on 45 percent to 41 percent, with 14 percent of voters still undecided.
The Opinium research agency said 49 percent of respondents to their survey of 1,156 backed staying in the union, with 45 percent set to vote for independence and six percent undecided.
Meanwhile, a Survation poll for the Scottish Daily Mail said 47.7 percent would vote "No" to independence, and 44.1 percent would vote "Yes", with 8.3 percent choosing "don't know".
An average of polls taken in the final week before the vote puts the race neck and neck, with "No" on 51 percent and "Yes" on 49 percent, according to research institute ScotCen.
"These polls -- like all the recent polls -- show that we are in touching distance of success on Thursday," said pro-independence Yes Scotland chief executive Blair Jenkins.
Jenkins said it would be a "knife-edge vote".
Record numbers of voters have registered for the referendum and turnout is expected to be very high.
"I think all the predictions would suggest a turnout in excess of 80 percent," Mary Pitcaithly, the chief counting officer who will read out the result on Friday, told BBC radio.
Polls open at 0600 GMT and close at 2100 GMT.
Nearly 4.3 million people have registered -- around 97 percent of eligible voters -- and the result is to be announced in the early morning.
Pro-union Better Together campaign director Blair McDougall said there would be no going back from the decision.
"This vote will go right down to the wire," McDougall said.
"No" supporters outside Scotland declared Wednesday a "Day of Unity", calling public rallies in cities including Belfast, London and Manchester on the evening before voting begins.
"While we do not have a vote, we have a voice. With this voice we ask only one thing: choose unity," the organisation wrote in an open letter to the people of Scotland.
As the vote loomed, Prime Minister David Cameron was forced to defend his handling of the referendum campaign.
Newspapers reported there was anger within his Conservative Party at a decision to promise new powers for the Scottish parliament in a last-minute bid to convince voters to stay in the union.
Several members of parliament told the Financial Times that Cameron would have to resign if Scotland voted for independence.
"I hope Scots vote to stay; if it goes wrong, however, the prime minister will have to decide what the honourable thing is to do," said Conservative MP Andrew Rosindell.