The TUC march for the alternative should be a "march of the mainstream", Ed Miliband has said.
Tens of thousands of people are expected to descend on London tomorrow in the first mass demonstration against the coalition's spending cuts.
Writing in the Daily Mirror, the Labour leader issued a clarion call for any Britons disassociated with the government's agenda to join the protest.
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"If anybody wants a reason to join this Saturday's demonstration, there are many - the need to show there is an alternative, to save our services, to show the cuts are going too deep and too fast," Mr Miliband wrote.
"But I would also urge people to join us to protect the promise we in the past have made to our children."
The Labour leader accused the Tories of maintaining "politics of division" and dragging the country back to the 1980s.
"These Tories - and their Liberal Democrat accomplices - remind me of the 1980s Tories: arrogant, uncaring and out of touch with people's lives," he said.
"They are trying to practise the politics of division - public against private sector, working people against those on benefits, one region pitted against another.
"But tomorrow tens of thousands of people will come to a march and rally in London to show there is an alternative.
"It should be a march of the mainstream."
Tomorrow's march is expected to see up to a quarter of a million people take to the streets, making it the biggest protest since the demonstration against the Iraq War in 2003, where 750,000 people turned out against the invasion.
The Metropolitan police have indicated 4,500 police officers will be mobilised, amid fears that the protest may be hijacked by violent splinter groups.
Conservative MP Greg Hands said Mr Miliband and Mr Barber had a duty to maintain order and keep extremist groups under control.
"This march is being organised by the TUC with Ed Miliband as the star speaker. Having decided to bring thousands of their supporters onto the streets, Mr Miliband and Mr Barber have a duty to ensure that their march does not become a focus for disorder and law-breaking," the London MP said.
"Ed Miliband should use his influence with the unions to ensure that the march tomorrow is not taken over by extremist groups. There must be no repeat of the violence we witnessed at several student marches last year."
During one of the largest tuition fees protests, students broke into Conservative party headquarters in Millbank, tearing down fixtures and forcing the evacuation of the building.