Ed Miliband will today launch an attack on Scotland's First Minister, claiming his drive for independence would fail to make the country a fairer place.
The Labour leader will use a speech to his party's Scottish conference in Dundee to argue against the "separatism of the SNP".
Other high profile figures in the party, including shadow foreign secretary Douglas Alexander and shadow defence secretary Jim Murphy, will also turn their fire on the Nationalists.
In his speech this afternoon, Mr Miliband will argue that at a time when the economy is "not working for the working people of our country", Alex Salmond's administration at Holyrood is "leaving more Scots out of work".
His address to the Dundee conference will build on a speech in Glasgow earlier this year, when the Labour leader insisted a "fairer, more equal and more just United Kingdom" would best be created by retaining the Union.
Today, Mr Miliband will attack Mr Salmond for his claims that an independent Scotland could be a "beacon for progressive opinion" for those south of the border.
He will tell conference: "Alex Salmond came to England to brag about how he would turn Scotland into a progressive beacon.
"There's just one problem. He forgot about what he had done in Scotland. When George Osborne handed him the plans to make cuts to capital spending of 11%, he didn't just make those cuts. He almost doubled them. Thousands of jobs building roads, bridges, and infrastructure ripped out of the economy, not just by the Tories, but by the SNP.
"He forgot about the people of Scotland when he cut the budget of colleges by a fifth, harming the training chances for young."
Mr Miliband will hit out at Mr Salmond's "SNP Government which blames everyone else while leaving even more Scots out of work".
And he will insist: "Throwing up new borders won't make Scotland fairer.
"If we are going to build an economy that works for working people, we have to do it together."
He will add: "If we are going to create a fairer tax system, we must avoid the race to the bottom on tax rates that separation would import.
"And if you want to create a country that is really a progressive beacon, why would you abandon the redistributive union that is the United Kingdom?"
With the Scottish Government not proposing to hold its referendum on independence until autumn 2014, Mr Alexander will tell the Nationalists: "You can try and delay the Scottish people's choice. But you will not change the Scottish people's verdict."
Labour, he will argue, should be "open minded" about devolving further powers to Holyrood, including fiscal powers but "must be resolute in our rejection of separation".
Mr Alexander will state: "As the authors of devolution, we must be both the defenders and developers of devolution.
"And let us tell the Nationalists with a quiet confidence that they can bully, they can bluster and they can boast, they can delay and dissemble, but on the issue of separation, they do not speak for Scotland."
Meanwhile, Mr Murphy will argue that "separation is a powerful idea from the 19th century entirely unsuited to the complexities of influence in the 21st century".
And he will ask: "How does Scotland get its way in the world if we leave the UK, the one country with the unique influence of being in the EU, Nato, the Commonwealth and the G8?"