A teachers' union in England is to ballot members on strike action after 87% of its members voted to reject the government's pay offer.
The NASUWT, which represents 280,000 teachers in the UK, said the offer failed to address its concerns over pay and working conditions.
Four unions have now rejected the offer - including the National Education Union, which is planning more strikes.
The government has said further strike action was "extremely disappointing".
Most state school teachers in England had a 5% pay rise in 2022.
They were offered a 4.3% rise next year, as well as a £1,000 one-off payment this year. Starting salaries would also rise to £30,000 from September.
The government said it believed schools could afford to fund most of the pay rise from their budgets, and that extra money would have been provided to make up the rest.
But unions have been campaigning for a fully funded pay rise, arguing that taking the money from schools' budgets could mean they have to make cuts elsewhere.
The government's pay offer has also been rejected by the National Education Union (NEU), the National Association of Head Teachers (NAHT) and the Association of School and College Leaders (ASCL).
At the NASUWT's annual conference in Glasgow on Saturday, Dr Patrick Roach, the union's general secretary, urged Education Secretary Gillian Keegan to return to pay talks.
"The government's pay offer failed to come close to addressing the concerns over pay and working conditions of teachers and this has rightly been rejected by our members," he said.
"Gillian Keegan has said that she is willing to negotiate and to listen to the profession. She must now demonstrate that she means what she says by getting back around the negotiating table to find a resolution to our dispute."
He said the onus was on the government to make a "fully-funded pay offer that will be acceptable to the profession".
The union did not reveal the turnout of the consultative ballot, but it said 77% of members said they would be willing to vote for strike action.
Members of the National Education Union in England - the UK's largest education union - will strike on Thursday 27 April and Tuesday 2 May.
In Northern Ireland, five teaching unions will strike on Wednesday 26 April.