Salmond: if you hold the balance, then you hold the power

The former First Minister, who is on course to return to the Commons in May, rejected the claim that his party would be in a weak bargaining position even if they win a large number of seats, as voting against Labour could lead to the Tories taking charge.

Mr Salmond said that he believed the SNP propping up a minority Labour administration on an issue by issue basis was the most likely outcome after May, and that Ed Balls would be forced to make compromises with the nationalists in return for support for his budget.

He added: "If you hold the balance, then you hold the power."

The ex-SNP leader, who also claimed that Scottish independence was almost inevitable at some point in the future, said: "Any minority government has to negotiate in order to win a majority for its proposal. That is patently obvious. To deny that is to deny reality.

"If the SNP are in these circumstances it will be very good for Scotland, certainly."

Mr Salmond was speaking as membership of the SNP hit six figures. Thousands of new members have joined the party following the No vote in the referendum on Scottish independence on September 18 and yesterday it had emerged that 100,000 people were signed up to the party.

Pressed on what kind of deal was possible with Labour, Mr Salmond said: "The Labour Party have ruled out a coalition but haven't ruled out a confidence and supply arrangement, where you have a set programme ... I think it is more likely to be a vote by vote arrangement."

Scottish Labour leader Jim Murphy hit back at Mr Salmond, saying the SNP would have "no bargaining chips" in negotiations with an Ed Miliband-led Government, and warning Scots that they could not vote SNP to get a Labour government "by proxy".

Meanwhile, the Tories released a new campaign video depicting Mr Salmond playing a pipe and Mr Miliband dancing, saying the SNP would 'call the tune' if it supported Labour in the Commons. It follows the launch of a poster, displayed in England, which depicted a tiny Labour leader in Mr Salmond's top pocket.

Tory MSP and chief whip John Lamont accused Mr Salmond of "stunning arrogance". He added: "Four weeks before postal ballots go out, Alex Salmond is taking the votes of people in Scotland for granted and planning back-room deals with Labour from a TV sofa in London.

"Now he is talking up the prospect of a vote-by-vote deal with Labour - one Ed Miliband still refuses to rule out. That would mean the SNP holding a weak Labour Party to ransom on every vote, every day, all with the aim of trying to weaken the United Kingdom."

Opinion polls have suggested that Mr Salmond is on course to win the Aberdeenshire seat of Gordon comfortably.

But Sir Malcolm Bruce, the Liberal Democrat incumbent who is standing down in May, predicted that Mr Salmond would be "shaken to his foundations" when voters rejected him in May in favour of his party's candidate, Christine Jardine.

Speaking on the final day of the Scottish Liberal Democrat spring conference in Aberdeen, Sir Malcolm said: "Christine and I are determined to ensure that his dreams in Gordon are ended on May 7 and that the people of Gordon are spared the nightmare of Alex Salmond treading the boards of a Westminster parliament he despises and claiming to represent them.

"He says he wants to shake Westminster to the foundations. Yet, everything he came into politics to achieve has been rejected here in the North East and I believe local people will reject him too. He will be shaken to his foundations. I know for sure Christine will serve the people of Gordon far, far better than he ever could."

The attack followed former Liberal Democrat leader Paddy Ashdown branding Mr Salmond's new book the "longest exercise in literary masturbation since politics began" on the opening day of the conference.

Mr Salmond responded by pointing out that there were more people at one of his book signing events in Aberdeen on Friday than delegates at the nearby conference.