Labour leader Ed Miliband has said his party will lead the battle against Scottish independence as he highlighted the "deep bonds" between the countries of the United Kingdom.
In his off-the-cuff party conference address in Manchester, Mr Miliband said Scottish independence would leave the UK worse off "in the soul of our nation".
He said: "There is no more important area of our common life than the United Kingdom itself. One of our four countries, Scotland, will decide in the next two years whether to stay or to go.
"I want to be quite clear about this: Scotland could leave the United Kingdom.
"But I believe we would be far worse off as a result, not just in pounds and pence, but in the soul of our nation.
"I don't believe that solidarity stops at the border. I care as much about a young person unemployed in Motherwell as I do about a young person unemployed here in Manchester.
"We have common bonds, we have deep bonds with each other - the people of Scotland and the people of the rest of the United Kingdom."
Setting out the strength of the links, he said: "If you think about the people of Scotland and the Olympic Games, they weren't cheering on just the Scottish athletes of Team GB, they were cheering on all the athletes of Team GB.
"That's what the SNP don't understand. Why would a party that claims to be left of centre turn its back on the redistribution, the solidarity, the common bonds of the United Kingdom?
"It is up to us, we the Labour Party must be the people who fight, defend and win the battle for the United Kingdom."