Two of the country's biggest trade unions have formed an alliance to campaign against the Government's austerity measures.
Unison and the GMB, which represent two million workers, said they will use their mutual influence to rally support for an alternative economic plan.
Dave Prentis, general secretary of Unison, said it was a historic move, adding: "Communities the length and breadth of the country are being ripped apart by Tory cuts, while the rich enjoy tax breaks, massive pay rises and bonuses.
"In the face of this continued attack on working people, it makes absolute sense for us to join forces and speak with one voice against this mindless austerity agenda which is only dragging the country down.
"We will campaign for the issues that really matter to our shared membership and, when the time is right, we will take action together. Independently we are strong, together we will be a force to be reckoned with."
Paul Kenny, GMB general secretary, said: "The destruction of services and jobs under the current Government cannot be allowed to continue without serious challenge.
"The latest announcement threatening to throw on to the streets tens of thousands of young people by ending their housing support whilst multimillionaire backers of (Prime Minister David) Cameron hide behind tax dodges is the final straw in the argument that we are all in this together."