The threat of co-ordinated strikes by hundreds of thousands of public sector workers in protest against cuts in jobs, services and pensions is set to come a step closer.
Delegates at the annual conference of the Public and Commercial Services union (PCS) are expected to agree to a national ballot for industrial action.
The union's leadership is pressing for a ballot for strikes and other forms of industrial action, and for talks with other unions to co-ordinate any protests.
Three teaching unions - the Association of Teachers and Lecturers (ATL), the National Union of Teachers (NUT) and the National Association of Head Teachers (NAHT) - have already agreed to ballot members over national strike action.
They are concerned that the Government's changes to public sector workers' pensions will leave them working longer, paying more and receiving less when they retire.
Both the NUT and ATL, traditionally seen as the most moderate teaching union, are due to begin balloting members within days.
If approved, these two unions could take strike action this summer, in a move that would affect millions of children at virtually every school in England.
Mark Serwotka, general secretary of the PCS, will tell the conference in Brighton: "This coming year is the most important year in our history as we face battles over jobs, privatisation, pensions, pay and our terms and conditions."
If the conference approves a strike ballot, voting among more than 250,000 PCS members will start next week, with the result due in mid-June.
The union represents workers across Government departments and agencies, jobcentres, tax offices, coastguards, driving instructors and courts staff.