Former chancellor Alistair Darling has insisted that the independence question must be settled before a detailed offer of more powers for Holyrood is made to voters.
The Better Together chief said Unionist parties were “broadly” agreed on a package of further devolution and people “know that change is coming” if they vote No.
Mr Darling, a Labour MP, spoke out after First Minister Alex Salmond claimed the No campaign was panicking because the Yes campaign was winning the argument.
The Better Together chief said the stakes could not be higher but was “very confident” the No campaign would win the contest on September 18.
A landmark YouGov survey suggested 51% of Scots would vote Yes and 49% No, but Mr Darling said he was not surprised by the finding because he always expected the polls to “tighten up” and “go to the wire”.
Asked if Better Together was playing into Yes Scotland’s hands by not making a firm offer before the referendum, he said: “It is some time now since the three non-nationalist parties put forward proposals to give the Scottish Parliament more power in relation to tax and welfare.
“They are broadly agreed, of course there are one or two details to be worked out, but that was the situation before the Scottish Parliament itself was set up.”
Mr Darling said he believed the majority of people wanted Scotland to remain part of the UK.
“It is the nationalists that are putting forward the case for leaving but they cannot answer basic questions on the currency, who is going to fund the NHS and how they are going to deal with the £6billion shortfall once you lose the extra public spending,” he added.
“We are winning the argument, we will win this referendum next week because people see the stakes could not be higher.
“We do not have to break up the UK for Scotland to become a better and stronger country in which to live.”