Labour suffered a blow yesterday after one of its 'big beasts' appeared to suggest the party's woes in Scotland could cost Ed Miliband the chance to form a majority government.
David Blunkett also described the SNP surge as a "Tsunami".
The Conservatives claimed that the former Home Secretary had hinted that Trident could be affected when he said a minority government could mean "the cutting-edge programmes that we want to see will have to be delayed until eventually we can win an overall majority across the United Kingdom."
However, Labour is expected to get enough backing from other parties, not least the pro-Trident Tories, to ensure it wins any parliamentary vote on the weapons system.
Mr Blunkett's comments come amid reports some Scottish Labour figures believe leader Jim Murphy should stand down if the party loses most of its seats next Thursday.
A new poll also suggested that Mr Miliband's campaign to become Prime Minister has stumbled.
Pollsters Ipsos Mori said that a UK-wide survey showed that the Conservatives had climbed two points in the past fortnight to 35 per cent, while Labour had dipped by five points to 30.
To add to the party's problems, the shadow Chancellor Ed Balls was forced to defend his senior colleague Margaret Hodge saying she had "paid the appropriate tax" following claims she received £1.5m shares from a tax haven.
Today Mr Miliband will kickstart the final weekend of election campaigning at a rally in Glasgow, as he attempts to boost his party's dismal poll ratings north of the border.
He will issue a warning to Scots saying: ""I don't want anyone here to look back and wish you had been part of the change we are going to make."
His speech will also hit out at the SNP saying: "Nationalism never built a school.
"It never lifted people out of poverty.
"It never created a welfare state that healed the sick and protected our most vulnerable.
"It is Labour values, Labour ideas and the determination of people across Scotland that has built this country to what it is today."
Earlier, Mr Blunkett said that the SNP "tsunami" currently sweeping Scotland could have "dangerous" consequences for the future of the Union.
He added: "Labour could win literally scores of seats in England and Wales and see themselves unable to offer a majority Labour government because of what has happened in just one part of the United Kingdom.
"Once people stop listening, once their minds have switched off to even rational argument, then it is extremely difficult to win that back. People are not even prepared to take leaflets or to engage in discussion.
"It is as though a great part of the Scottish nation have switched off and that is so dangerous for the Union and the future of Britain as a whole."
He predicted that if the result led to the formation of a minority Labour government, Mr Miliband would have to reach out to voters who had backed the nationalists, as well as Tory and the Liberal Democrat supporters.
"I think it is going to have to be what you might describe as more-than-grown-up politics - it is going to have to be about re-shaping the way in which Westminster operates," he said.
"An incoming Labour government led by Ed Miliband will have to reach out across political divides to people who have voted Conservative and Lib Dem as well as to those who have voted SNP to be able to say that we have to do what is right for the nation."
A Labour spokesperson said: "We are fighting hard for every seat, to win a majority. This is yet more scaremongering from the desperate Tories.
"There will be no coalition with the SNP. We will be presenting a Labour Queen's speech based on our manifesto. How other parties would choose to vote is for them."
In Glasgow, Mr Miliband will call on people across Scotland to help elect a Labour Government.
He will say: "I want the people of Scotland to join me, join Labour, join people across the United Kingdom, in making it happen.
"We could be under a week away from a Labour Government."
He will point to Scotland's record in helping to change the UK, saying: "Throughout Scotland's history you have always been part of change.
"Always led change.
"Imagine all the people you know who have built Labour in Scotland.
"Your grandparents who fought for their rights in the shipyards and mines across this country.
"Your mums and dads, many of whom delivered leaflets for Labour or knocked on doors.
"And remember our great leaders.
"From Kier Hardie to Jennie Lee.
"John Smith to Donald Dewar.
"What would they want today?
"We could be on the verge of electing a Labour Government.
"They would want to be part of it."
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