Wendy Alexander was called “a busted flush” yesterday by one of her closest colleagues as the gulf between her and Gordon Brown over an independence referendum grew wider than ever.

The comment about her leadership came as Ms Alexander said that Labour MSPs would not vote against an SNP referendum Bill in 2010 on the same day that the Prime Minister said he was “not persuaded” of the need for such a vote.

The Scottish Labour leader said in a television interview: “We will not vote down the opportunity to let the Scottish people speak.” Her words effectively opened the door to a Nationalist victory when the Bill comes to a vote in the Scottish Parliament in two years’ time.

Ms Alexander’s continued defiance of Mr Brown, her long-time friend and ally, came amid the first rumblings of discontent in the wider Labour Party in Scotland about the shambolic way that she is seen to have handled the referendum issue and the damage that the affair has done to the party north of the Border.

One senior and influential figure in the Scottish party told The Times: “She is as close to a busted flush as you can get, but what keeps her alive as the leader in Scotland is that there is simply no alternative. She is losing the belief of the party in Scotland and her own group in the Scottish Parliament.”

Ms Alexander, meanwhile, was forced to go back on her claim last week that Mr Brown had endorsed her call for an early referendum on independence. Yesterday she said that he had merely given her his support “to pursue whatever tactics I thought right to expose the hollowness of the SNP’s position”.

The Nationalists claim that 80 per cent of Scots want a plebiscite on separation from the rest of Britain but have postponed holding one until the autumn of 2010.

The issue of Labour’s position on a referendum has convulsed the party in Scotland, embarrassed the Prime Minister and left the leadership north and south of the Border adopting two clearly different positions.

It began when Ms Alexander challenged Alex Salmond, the Nationalist First Minister, a week ago to “bring it on”, arguing that she did not fear the verdict of the Scottish people. Aides added that she wanted a referendum before 2010.

Ms Alexander then said that she had not ruled out a Bill of her own in the Scottish Parliament to force the SNP’s hand but the plan began to take on the appearance of farce when Mr Brown, in the Commons on Wednesday, failed to back her. On Thursday, Ms Alexander said that she was sticking to her guns.

On Saturday, after a meeting of Labour’s Scottish executive committee, Ms Alexander said that she had ditched her strategy of trying to force the SNP into an early referendum. Yesterday, in an interview on the BBC’sPolitics Show, Ms Alexander again defied Mr Brown by saying: “The decision as to whether a referendum should be supported in the Scottish Parliament is a matter for the Labour group in the Scottish Parliament . . . The Prime Minister has endorsed my right as leader of Labour in the Scottish Parliament to do whatever we think it takes to expose the hollowness of the SNP.”

Asked if she was saying that Labour would support an SNP Bill in 2010, she said: “There are no blank cheques here. We want to see a Bill. We want to see the question. We have called the SNP’s bluff. They will not let the Scottish people speak.”

Crucially, she added: “We will not vote down the opportunity to let the Scottish people speak. We will harry them on things like what the question is and what the process is. It is right that after 30 years Scotland should be given the chance to speak.”

The interpretation being put on Ms Alexander’s words was that, at worst, Labour would abstain when it came to a vote on backing a referendum, citing its disapproval of the question as the reason.

A Labour abstention would mean that the SNP would still have enough support from its 47 MSPs, two Greens and one Independent to carry the day against 17 Tories and 16 Liberal Democrats.

Mr Brown had pledged yesterday to do “whatever is necessary” to preserve Britain in the face of SNP demands for Scottish independence.

In an interview with theSunday Telegraph, the Prime Minister called for pro-Union parties to join with business groups and trade unions to campaign against a break-up of Britain. “Some issues are bigger than party politics and need to be addressed in the common interest,” he said. “I will do whatever is necessary to ensure the stability and maintenance of the Union.”

Mr Brown also defended Ms Alexander as an “excellent leader” but distanced himself from her call, saying that he was personally “not persuaded” of the case for a referendum.

Ms Alexander’s brother Douglas, the International Development Minister, reinforced Mr Brown’s position and said that he was “not convinced” that now was the right time to hold a referendum.

Brian Wilson, a former Westminster energy minister, said: “To commit to a referendum which ultimately only the UK Government can deliver, without checking out what the UK Government thinks when it is of the same party – I think carelessness would be an understatement.”

Nicola Sturgeon, the SNP deputy leader, branded the Scots Labour leader as “comical Alexander”, saying that she had effectively conceded that she misled the people of Scotland last week by saying that Mr Brown had endorsed her call for a referendum. “It makes her position impossible and untenable,” Ms Sturgeon added.

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