By Belinda Goldsmith
LONDON (Reuters) - Scotland's vote on leaving the United Kingdom will be close but the economic argument for the 307-year union with England will sway many undecided voters, the head of the anti-secessionist campaign said on Wednesday.
In the biggest challenge to the union since Irish nationalists created a breakaway republic almost 100 years ago, about 4 million residents of Scotland over the age of 16 will vote on Sept. 18 on whether to declare independence from London.
Polls indicate Scots will vote to stay in the United Kingdom but a large number of still undecided voters and the risk of unexpected events means the ballot will be tight, said Alistair Darling, head of the Better Together campaign against secession.
"It is going to be closer than people think - what matters is who turns out on the day," said Darling, a Scot who served as Britain's finance minister from 2007 to 2010 under former Labour Prime Minister Gordon Brown.
"There is still a very substantial group of people who as I say are being pulled both ways, head and heart, so we shall have to see what happens to them on the day," he told Reuters in an interview.
Darling said the economic argument for keeping Scotland within the United Kingdom would ultimately sway many undecided voters. Polls show up to 20 percent of Scottish voters have still not made up their minds.
NEED FOR CLEAR WIN
He said the economy had emerged clearly as the main issue for voters keen to know how independence would affect their pensions and jobs.
But he said those opposing secession needed to deliver a healthy win to close the question for a generation and let Scotland move on to tackle other issues.
"They only need to win once, by one vote, and there is no going back," Darling said. "We need to win well to put the thing to bed for a generation."
"And the closer it is, the greater the risk that they say: 'Well we didn't this time but we will be back again next year'," he said, adding that there was evidence of some voter fatigue over the referendum that was agreed in early 2012.
Darling said some voters were now taking more notice of celebrities than politicians, for example singer David Bowie, who in February urged Scots not to leave the United Kingdom in a statement delivered at an awards ceremony by model Kate Moss.
"Here was someone who they had heard of who was not a politician and they talked about it," Darling said.
But on a darker note, Darling said he was angry at the abuse leveled against those who had voiced their views on independence.
"One of our problems has been to get people to speak out and we keep coming back to this massive problem that when people have spoken out they are subjected to attacks. It really reflects very badly on Scotland," Darling said.
He said one opponent of independence had chosen to stay away from the public debate out of concern about the possible abuse that speaking out could provoke.
MORE LOCAL POWER
As leader of the Better Together campaign, Darling has argued the unionist case shared by all of Britain's three main political parties, namely that Scotland is better off remaining inside the United Kingdom but with greater autonomy.
Nationalist leader Alex Salmond, who runs Scotland's devolved parliament, says Scotland has suffered centuries of mismanagement by far-off leaders in London and independence plus control of a share of North Sea oil would make it a rich nation.
After months of wrangling over the economy, the currency of an independent Scotland and European Union membership, the major UK parties have started to woo voters with promises of more powers for the Scottish parliament if there is a "No" vote.
"I am in favor of the Scottish parliament having the power to raise money as well as to spend it," Darling said.
"All three parties to varying degrees are now in favor of that ... and it would be extremely helpful if the three parties were to enter into a process that would allow you to see where is the common ground."
Asked about his longer-term political ambitions, Darling said he was waiting until after the vote to decide whether to stand again for parliament in the 2015 general election.
"One of the big assessments that I will make is how I feel on Sept. 19," said Darling, 60, who represents a constituency in Edinburgh. "Obviously the result will have a huge bearing on what I might decide to do."
(Editing by Guy Faulconbridge and Tom Heneghan)