The bitter dispute over public sector pensions will reach a new phase when the last major union involved in the row announces the result of a strike ballot.
The NASUWT teaching union has balloted more than 200,000 of its members over industrial action and, if approved, they could join the mass walkout on November 30 in protest at the Government's controversial pension reforms.
A series of unions representing teachers, civil servants, NHS and council workers have already declared their ballot results, setting themselves on a collision course with the Government.
More than 227,500 NASUWT members have voted in the first national industrial action ballot the union has called in over a decade. The union has lodged a formal trade dispute with the Government over workload, conditions of service, pensions and jobs.
General Secretary Chris Keates said the decision to hold a ballot had not been taken lightly. He said: "Ministers have ploughed on relentlessly with policies and plans which have taken their toll on morale and motivation, making it increasingly difficult for teachers to continue to do their best for children and young people.
"Over half of teachers now report that they have seriously considered quitting teaching altogether in the last 12 months. Only the recession is preventing a mass exodus."
Probation officers, bus drivers, police civilians and museum staff were among the latest workers to back a pensions strike on Thursday. Unite said 75% of those who took part in its ballot said yes to taking part in the strike, with a 31% turnout covering over 200 employers.
Labour leader Ed Miliband urged both sides in the dispute to negotiate, saying: "There is a huge responsibility on both sides, even at this late stage, to stop the strike happening. The unions need to show that they are willing to negotiate, the Government needs to show that it too is willing to negotiate."
Over two million workers are now set to walk out on November 30 for a day of action co-ordinated by the TUC, which will disrupt schools, courts, government offices, jobcentres, driving tests, council services and hospitals.
Cabinet Office Minister Francis Maude said: "We have listened to the concerns of public sector workers about their pensions and responded with a new generous settlement which is beyond the dreams of most private employees. I urge the trade unions to devote their energy to reaching agreement and not to unnecessary and damaging strike action, which is often on the basis of low turnout."