But his warning was dismissed by the Nationalists, who insisted the vote on May 7 was not about independence and said a strong SNP block of MPs would work for progressive policies, including an end to the cuts, across the UK.
With a poll showing almost 30 per cent of Scots are still undecided, Mr Balls, on a visit to Glasgow with Scottish Labour leader Jim Murphy, rejected the SNP’s claim that its top priority was ending austerity.
He said: “I’m saying to all those undecided voters, ‘think hard about this’. A vote for the SNP is a vote for plans which extend austerity and let the Tories back in.
“SNP MPs aren’t trying to go to Westminster to fight poverty, they want to go to Westminster to fight for another referendum.
“That is why we do face two roads and we’re going to decide in the next ten days which road to take – Labour’s road, a better plan, a road to an economy which works for working people, or a road to another referendum. That’s the choice.”
He was speaking as a poll by TNS put support for the SNP at a record 54 per cent, up two percentage points from the previous poll, compared with 22 per cent for Labour.
But SNP leader Nicola Sturgeon said her party would work “positively and constructively” at Westminster for people throughout the UK.
In a radio interview, she said: “We remain part of the Westminster system and therefore I would say to people outside Scotland we can be trusted because as long as Westminster decisions affect Scotland it matters to the SNP and it matters to Scotland that those decisions are good decisions.”
The election was not about independence or another referendum, she said.
“Even if we won every seat in Scotland, that would not be a mandate for a referendum.”
On the expected election result, she said: “What may happen is that voters reject the two-party Westminster system and what we are seeing is the heralding in of a new age of multi-party, multinational politics.
“I think it could be a breath of fresh air for voters in Scotland, [and] for voters across the UK as well.”
Labour leader Ed Miliband said at the weekend he was not interested in any deals with the Nationalists.
But on a campaign visit to Glasgow, Len McCluskey, head of the Unite union, said he fully expected Mr Miliband to work with the SNP.
He said: “I’m expecting Ed Miliband to be prime minister and in those circumstances I would expect him to work well with any progressive party who seeks to support the vision that he has of changing Britain for the better.”
On the buses
Ed Miliband has revealed his childhood dream was to become a London bus conductor. The revelation came on a visit to Stockton-on-Tees when a boy asked him what he wanted to be when he was seven years old.
Nicola mixes it up with homes plea
First Minister Nicola Sturgeon picked up some kitchen tips as she visited The Cook School Scotland in Ayrshire.
She was there to set out the SNP’s plans to push the UK government to fund 100,000 affordable homes across the UK per year as part of the party’s opposition to austerity.
She said: “Making sure more people have the opportunity to live in high quality, affordable housing is such an important part of making life better for many across Scotland.
“We will call for the UK government to put in place a new target to build 100,000 affordable homes each and every year. This will help grow the Scottish housebuilding industry, supporting around 6500 jobs, economic growth and much needed quality housing across the country – and will help undo at least some of the damage of Westminster cuts.”
Lib Dems air NHS concerns
Liberal Democrats have called on SNP ministers to step up support for NHS staff after a survey found one in ten nurses was forced to use time from their annual leave to complete mandatory training courses.
The RCN survey also found over half of nurses on such courses said no cover was provided while they were absent.
Scottish Lib Dem health spokesman Jim Hume said: “It’s unacceptable that the Scottish Government has failed to ensure our NHS has the number of nurses needed to alleviate pressure on our hospitals. Nurses work incredibly hard. It isn’t fair that they are being forced to use their own time like this.”