The prospect of a massive strike by public sector workers over pay has increased after local government members of Unite strongly supported industrial action.
The union announced that its council members in Wales, England and Northern Ireland voted by over 2-1 to go on strike in protest at an offer worth 1% for most employees.
Unite will now join a 24-hour walkout on July 10 - the biggest day of action over pay the Government has faced since it came to power.
Local government members of Unison and the GMB have also backed strikes, while the National Union of Teachers said it will also take part as it continues a long-running row with the coalition over workload and other issues.
Civil servants in the Public and Commercial Services union are also embroiled in a bitter dispute over spending cuts, pay and privatisation, and the Fire Brigades Union continues to campaign against the Government's controversial reforms to firefighters' pensions.
Health workers in England are also in dispute over pay after the Government refused to accept a recommended 1% rise, and could be balloted for strikes later this year, threatening industrial action in the autumn as well as in the run up to next year's general election.
Unite members voted by 68% to go on strike and by 79% for other forms of industrial action.
National officer Fiona Farmer said: "Our members have endured four years of pay cuts in real terms and they have now voted overwhelmingly to strike on 10 July to drive home the message to ministers that poverty pay in local government must end.
"The depth of feeling on the pay issue is reinforced by the fact that local government unions, GMB and Unison, and members of the National Union of Teachers are all taking action on 10 July.
"Poverty pay is widespread across local councils. Household bills continue to soar, but our members' buying power is constantly being eroded. The national minimum wage will soon overtake local government pay scales and members are choosing between heating and eating.
"For too long the council workers have been targeted to bear the brunt of the austerity measures that have been imposed by millionaire Cabinet ministers since 2010.
"The aim is to get the employers back around the table to negotiate a fair deal for those who deliver vital local government services, from social care to refuse collection, on a daily basis."
Unite did not ballot its members in Scotland where the devolved administration has agreed to pay the Living Wage to all council staff - currently £7.65 an hour and £8.80 in London.
Unite has about 70,000 members in local government carrying out such jobs as refuse collection, street cleaning, maintenance of council property, traffic enforcement, school support and care services, and grave digging.
Conservative Party chairman Grant Shapps said: " Ed Miliband promised that he would support the Government's difficult decisions on public sector pay, to help reduce the deficit.
"If he is serious about this he must condemn this disruptive strike and refuse to take any more cash from Len McCluskey's Unite.
"Otherwise people will conclude that he just can't stand up for Britain against demands from his union bosses for more spending, more borrowing and more taxes."
A Local Government Association spokesman said: "It is disappointing that Unite will be proceeding with strike action when the turnout was so low.
"Overall, only 8% of the total workforce have voted for this strike. Local government staff have worked wonders while councils have been tackling the biggest funding cuts in living memory and we have no doubt that many will still be at work on the day of strike action
"The pay offer we have made would increase the pay of most employees by 1% while the lowest paid would receive an increase of more than 4%. This is the fairest possible deal for our employees given the limits of what we can afford. This strike will not change the pay offer we have made, but it will mean those who take part lose a day's pay."