The First Minister has always spoken out vociferously against independence.
But last night he was pressed for the first time on the actual principle of a referendum to decide the issue and he appeared to suggest that it might have his backing, in the future.
Speaking on STV's Scotland Debates programme, which featured the leaders of all the main parties north of the Border, Mr McConnell was adamant that the SNP's plans for a referendum in the next four-year term of the Scottish Parliament would be disastrous for business and the Scottish economy.
Mr McConnell, said: "There is an issue about the referendum and normally I would support a referendum on an issue because it gives a chance for people to express their view.
"But a referendum on independence for Scotland in three years' time would lead to a level of uncertainty in our economy and this election has to be about the Scottish economy and the way in which we as a nation build up that economy, it would lead to uncertainty in our economy that would have a dramatic impact on people's jobs."
He was then asked: "You are saying it's just not the right time for a referendum on independence, you say a referendum on independence is not necessarily wrong, it's just the wrong time for it?"
The First Minister replied: "The policy on a referendum that is on offer in this election is a referendum in three years' time in Scotland."
And he was asked again: "But you're not against the independence referendum?"
The First Minister replied: "There could be an issue about that in the future."
Angus Robertson, the SNP's election campaign manager, said afterwards: "Mr McConnell has wobbled on the issue of a referendum, and has holed Labour's scaremongering campaign."
However, David Cairns, for Labour, said the key to the debate was Alex Salmond's admission that, if a referendum was defeated, the SNP would ask for a mandate from the Scottish people at the next election.
Mr Cairns said: "Years and years of endless turmoil would be the only result of an SNP administration at Holyrood."