The UK's largest teaching union will "make Labour MPs pay a high political price" if the government does not offer teachers in England a fully funded, above-inflation pay rise, its general secretary has said.
Daniel Kebede said members of the National Education Union (NEU) "expect better from a Labour government" than the pay recommendation ministers have made.
He said NEU members would campaign in Labour constituencies if it did not change - and "stand ready to strike".
Education Secretary Bridget Phillipson has said "any move towards industrial action by teaching unions would be indefensible".