Jury Out on Scotland Secession on Eve of Vote

On the eve of Scotland's independence referendum, the fate of the United Kingdom rests on hundreds of thousands of wavering Scottish voters as opinion polls showed supporters of the 307-year union just a whisker ahead of secessionists.

In an intense final day of campaigning, leaders of both sides beseeched Scots to seize the reins of history in a vote that has divided families, friends and lovers but also electrified this country of 5.3 million.

From the remote Scottish islands of the Atlantic to the toughest city estates of Glasgow, voters will be asked on Thursday to answer "Yes" or "No" to the question: "Should Scotland be an independent country?".

Four surveys - from pollsters Panelbase, Survation, Opinium and ICM - showed support for independence at 48 percent compared with 52 percent for the union, while a fifth, from Ipsos MORI, showed it even closer on 49 to 51 percent.

The surveys also showed as many as 600,000 voters remained undecided with just hours to go before polling stations open at 0600 GMT on Thursday.

"Don't let this opportunity slip through our fingers. Don't let them tell us we can't. Let's do this," Alex Salmond, Scotland's 59-year-old nationalist leader, said in an open letter to voters as he crisscrossed Scotland.

Invoking 18th-century economist Adam Smith and Scotland's greatest poet Robert Burns, Salmond implored Scots: "Wake up on Friday morning to the first day of a better country."

With a mix of shrewd calculation and nationalist passion, Salmond has hauled the "Yes" campaign from far behind to within a few percentage points of winning his dream of an independent Scotland.

Facing the biggest internal threat to the United Kingdom since Ireland broke away nearly a century ago, Britain's establishment - from Prime Minister David Cameron to corporate bigwigs and pop-culture celebrities - have united in a last-ditch effort to convince Scots that the United Kingdom is "Better Together."

Cameron's job could be on the line if Scotland breaks away, but the 47-year-old prime minister has conceded that his privileged English background and Conservative politics mean he isn't the best person to win over Scots.

That has left the leadership of the unionist case in the hands of the opposition Labor party, winner of 41 Scottish seats in the 2010 British election and the only party with the local support capable of checking the secessionist Scottish National Party.

Former Labor Prime Minister Gordon Brown, a Scot who has in recent days led the battle cry for the union, warned Scots in Glasgow, Scotland's biggest city and a crucial battleground, that Salmond was "leading us into a trap."

"Have confidence, stand up and be counted tomorrow," Brown thundered, fists clenched, to applause and cheers from unionist supporters. "Say to your friends, for reasons of solidarity, sharing, pride in Scotland, the only answer is vote 'No'."

A UNITED KINGDOM?

In the event of a vote for independence on Sept. 18, Britain and Scotland would face 18 months of talks over how to carve up North Sea oil and what to do about European Union membership and Britain's main nuclear submarine base.

Scotland says it will use the pound after independence but London has ruled out a formal currency union, while Britain will have to decide what to do about the nuclear submarine base on the Clyde, which the nationalists want to eject.

The prospect of breaking up the United Kingdom, the world's sixth-largest economy and a veto-wielding permanent member of the United Nations Security Council, has prompted citizens and allies alike to ponder what would be left, while the financiers of the City of London have warned of market turmoil.

Salmond has accused London of orchestrating a campaign by business leaders aimed at spooking Scots after businesses from BP to Standard Life cautioned about the risks of independence.

The United States has made clear it wants Britain to remain a "strong, robust, united and effective partner," in President Barack Obama's words, while saying it was Scotland's choice.

"I hope the Scots people will vote to remain in the UK," former U.S. President Bill Clinton said, warning of substantial financial risks and long divorce talks.

In England, Cameron admitted to the Times newspaper that he woke up at night sweating over the possibility of defeat in Scotland.

"We have set out how Scotland can have the best of both worlds," Cameron told reporters later.

In a bid to blunt Salmond's argument for breaking away, Britain's rulers promised to guarantee Scotland high levels of state funding and grant Scots greater control over finances.

British leaders accept that even if Scotland votes to keep the union, the United Kingdom's structure will have to change, as granting further powers to Scotland will provoke calls for a less centralized state from voters in England, Wales and Northern Ireland.

TOO CLOSE TO CALL

Four of the polls showed nationalists had gained ground, but the fact that supporters of the union were slightly ahead prompted investors to buy the pound, extending sterling's gain against the dollar. One poll, from Panelbase, showed support for independence had slipped to 48 percent from 49 percent.

In an indication of how close the vote is, the Scottish edition of Rupert Murdoch's Sun newspaper declined to take sides. As Scotland's best-selling daily, its stand had been eagerly awaited, but it said in an editorial simply that it believed in the people of Scotland to make the right decision.

Hundreds of independence supporters rallied in Glasgow, Scotland's biggest city, on Wednesday, chanting "Yes, we can and we will" and listening to speeches by activists on the steps in front of the Royal Concert Hall.

Supporters of the union also rallied in the city, imploring voters to "Love Scotland. Vote no."

With more than 486,000 voters, Glasgow is a crucial battleground, and the way its traditional labor supporters go could be decisive.

Electoral officials said the result of the vote is expected by breakfast time on Friday morning, but partial results will give an indication of the trend after the count of major cities such as Glasgow are declared around 0400 GMT.

Edinburgh and Aberdeen, which with Glasgow make up nearly a quarter of the vote, are also expected round about that time. Helicopters will fly from specially lit landing sites from remote islands.

Police played down the prospect of violence, and the leaders of both campaigns have said they will accept the will of the people no matter what the result and seek to work for Scotland.

In such a tight vote, the will of the people could depend on swaying those who even at this late hour have not made up their minds.

"I am still undecided," voter Karen Wood told Reuters in Edinburgh on Wednesday. "At the moment it is just the uncertainty of what Scotland has got in store for everyone. It's worrying. It is just such a huge decision to make."

(Additional reprting by Alistair Smout in Glasgow and Kylie MacLellan in London; Editing by Anna Willard and Will Waterman)