We have to beat Labour to be in a position to win political leadership

John Swinney

Mr Neil said people would be deterred from supporting independence in such a context by economic and other worries and that an election itself should be the mandate for independence.

The negotiated settlement with London could then be presented to the people for endorsement.

In the webcast, the contenders also discussed the fuel crisis, education, the economy, the quango state and the monarchy.

However, it was when the two candidates began discussing constitutional matters that marked differences emerged.

The candidates debated a range of issues

After an exchange on the merits and demerits of devolution, BBC Scotland Political Editor Brian Taylor referred to an email from a user from New Jersey who asked the candidates what they saw as the "largest single obstacle to independence".

Mr Swinney said: "There are two large obstacles. One is the political leadership of Scotland, that is the Labour Party. We have to beat Labour to be in a position to win political leadership.

"And the second is the need to build up self confidence within Scotland. To believe that our country, despite 300 years of being told that we're not up to the job, that we've got the resources, the skills and the strength of the people to actually govern ourselves."

Mr Neil said he agreed with Mr Swinney that the Labour Party had "lowered the horizons of the Scottish people".

However, Mr Taylor pressed the contenders on when the Scottish people could be asked to decide on independence.

We wouldn't be in the situation where we could run the referendum

Alex Neil

Mr Swinney said: What I want the SNP to do is to go into every election in the future, setting out the case for Scottish independence, putting out persuasive and convincing arguments as to why Scotland would be a better country under independence."

Mr Neil said he did not share Mr Swinney's view that a majority of Scottish seats in Westminster would clear the way for referendum on independence because the dominant UK or Scottish parliamentary party - both currently Labour - would stymie the vote.

"Who would run the referendum?" he asked. "It would have to be Donald Dewar or Tony Blair because the SNP wouldn't be in the government. We wouldn't be in the situation where we could run the referendum.

"They would decide the question, they would decide the date, they would decide the rules.

"Then you would go into the referendum and somebody says to you, 'what would happen to my pension, what would happen to the oil money?'.

Elected president

"The answer is you don't know because you haven't worked out the detail. Two years ago we had a referendum on devolution but we had a white paper which spelt out in detail what it would mean and I don't believe the Scottish people would give us a blank cheque."

Further occasional differences on policy had emerged during the debate.

Mr Swinney said he would retain a modernised monarchy - while Mr Neil, if forced to choose, would opt for an elected president.

On the issue of fuel duty, Mr Swinney said the SNP would advocate a cut of two pence per litre, while Mr Neil said a 20% reduction would address public concerns.