Leaders of 1.5 million council workers have warned that industrial action looks "inevitable" in a dispute over pay.
Unison, the GMB and Unite attacked employers for not making a pay offer amid suggestions that any rise will be pegged at 1% or be dependant on an increase in the national minimum wage later in the year.
The unions said in a statement that they "deplored" the employers' failure to make an offer at a meeting earlier this month and rejected any pegging of pay to the national minimum wage.
"We reiterate the view expressed by our members last year that 1% for 2014/15 will not be acceptable.
"The trade union side believes industrial action looks inevitable and is preparing accordingly."
Brian Strutton, national officer of the GMB, said: "The idea that one and a half million council workers should have to sacrifice part of a paltry 1% pay pot to meet their employers' statutory obligation to pay the national minimum wage is unacceptable.
"GMB and the other unions are further incensed that the employers say the pay pot is not negotiable. We have no choice but to begin preparations for consulting our members on industrial action."
Unions said council workers have suffered a three-year pay freeze, 440,000 job losses, and cuts to terms and conditions.
The dispute covers staff in England, Wales and Northern Ireland, ranging from street cleaners, school dinner staff and refuse collectors to social workers, gravediggers and classroom assistants.