Thousands of civil servants have voted to strike in a long-running dispute over job cuts, privatisation and pay.
Strikes will affect more than 200 government departments
Public and Commercial Services Union members will hold a 24-hour walkout on 31 January. Staff in 200 government departments are expected to take part.
Job Centres, benefit offices, courts, driving examinations and many other services will be hit by the stoppage.
Cabinet Office minister Pat McFadden said there was no need for strike action by PCS members.
"The government values the civil service highly. If PCS members have concerns about job losses or pay there is an established industrial relations process to discuss these issues," he said.
The union is striking over tens of thousands of job cuts recommended in the 2004 Gershon Review, as well as up to 12,500 predicted job losses in HM Revenue and Customs and further issues of pay and privatisation.
The PCS union predicts that more than 200,000 civil workers will go on strike, coinciding with the last day people can send in tax returns without getting a £100 fine, to cause maximum disruption.
A "second wave" of industrial action, including overtime bans, is planned for the run-up to the local elections in May.
Of the 280,000 members balloted, 61,488 voted in favour of the strike and 38,823 voting against.
General Secretary Mark Serwotka said the size of the majority showed the anger at the way civil and public servants were being treated.
Mr McFadden said the PCS was the only civil service union to ballot for strike action.
"We will do everything we can to avoid compulsory redundancies but cannot give guarantees it will never happen throughout the efficiency savings (Gershon) process."
Mr Hain is bidding to be deputy leader
Labour MP John McDonnell, who has said he wants to be the next Labour leader, has urged the prime minister and chancellor to intervene.
"The result demonstrates the strength of feeling and anger among the very people we rely on to deliver public services," he said.
Secretary of state for Northern Ireland and for Wales - and a deputy Labour leadership hopeful - Peter Hain, said there was a need for a better relationship between unions and Labour Party leaders.
'Not caving in'
"I think it's fallen into disrepair in recent years, but this is not about caving in to any old demand or about a return to the happy-go-lucky attitude to strikes. It's about a better partnership," he said.
Some commentators believe the unions are in a strong position to get more concessions out of the government, as the new prime minister will need their financial support in the wake of the cash-for-honours investigation.
TUC general secretary Brendan Barber told the BBC he wanted to see a change when Tony Blair steps down.
"We want to see an approach that brings the workforce together with people managing our public services to deliver real improvements rather than have change forced through."
But Mr Barber said the relationship was not one "where the unions are trying to squeeze concessions on the basis of trying to bully the leadership of the Labour Party".