Teachers could ballot on national strike action if substantial pay rises of 5% or more are not agreed by the government.
Members of the Nasuwt union will vote on proposals for a rolling programme of industrial action, while the National Education Union is set to vote on plans for a strike ballot.
The pressure comes after NHS staff were offered a 6.5% rise over three years.
The Department for Education says teachers get £37,400 on average a year.
That rises to £41,900 in London, it says.
Both the National Association of Schoolmasters and Women Teachers and the NEU – formerly the National Union of Teachers – are meeting for their annual conferences this weekend.
The unions represent the vast bulk of teachers who belong to a trades union in England, Wales and Northern Ireland.
In Birmingham, the Nasuwt is debating plans which could include “rolling strike action if governments, administrations and employers fail to agree to substantial, above-inflation and across-the-board pay increases next year”.
While the NUT motion, being heard in Brighton, claims teachers’ pay has fallen 20% in real terms since 2010.
It instructs the union to “launch a vigorous campaign on teachers’ pay”, calling for salaries to be restored to 2010 levels over the next three years.
It also urges the union’s executive to work with other teacher unions on submitting a joint pay claim for school workers, along the lines of that given to health workers – and for an initial pay hike of 5% “to begin restoring the cuts in living standards all school staff have suffered”.
In its report last year, the School Teachers Review Body (which advises government on teachers’ pay levels) said schools were facing substantial pressures in recruiting and retaining staff and that many were facing reductions in funding and growing cost pressures.
A number of unions have called on the STRB to recommend a 5% rise for teachers from this September, fully funded by the government.
Previous limited rises have had to be found from school budgets.
NEU general secretary Kevin Courtney said: “The funding crisis is really paying into the workload crisis which is really playing into the teacher recruitment and retention crisis.”
Nasuwt general secretary Chris Keates said radical and urgent action was needed to close the gap between teaching and other graduate professions.
The Nasuwt has 280,000 members while there are 400,000 in the NEU, which was formed after a merger between the National Union of Teachers and the Association of Teacher and Lecturers.
Department for Education spokeswoman said: “We have a record 15,500 more teachers in our classrooms than in 2010 and this generation of teachers is better qualified than ever before.
The average teacher’s salary stands at £37,400 outside of London, rising to £41,900 in the capital.
“It is thanks to these teachers’ hard work and our reforms that 1.9 million more children are being taught in good or outstanding schools since 2010.
“We want to continue to attract and keep the best and brightest people in our schools.”