Thousands of teachers could be walking out of the classroom next month as Ireland's largest teachers' trade union has announced its intention to ballot its members for strike action.
The news comes on the eve of the biggest teachers' strikes in recent years, which is expected to go ahead tomorrow despite pleas from the Education Minister to call it off.
A number of schools are expected to close either partially or fully when members of the largest teachers' union in Northern Ireland - the NASUWT - take part in the industrial action.
Only the Belfast and Newtownabbey areas will be affected tomorrow, and striking teachers will take part in a rally at the Europa Hotel in Belfast city centre this morning.
Education Minister Peter Weir has repeatedly urged the NASUWT to call the action off, saying it will be "detrimental" to pupils and union members.
The action comes after negotiations between the five teachers' unions and employers collapsed without agreement earlier this year. The unions rejected an offer that would have seen their pay frozen last year and a rise of 1% for 2016-17.
Tomorrow is set to be the first wave in a series of strikes across Northern Ireland over the coming months. Last night, the Irish National Teachers' Organisation (INTO) said it had sent letters to its 7,000 members after an "insulting" pay offer from Stormont after 13 months of talks failed.
The union said it is seeking a mandate to embark on a series of strikes in December and also said it will withdraw its co-operation with school inspectors to further escalate its campaign for a fair wage increase for teachers.
Gerry Murphy, INTO's Northern Secretary, said prolonged negotiations with the Department of Education, and the Employing Authorities, have been a genuine attempt to resolve the pay issue.
But he claimed the employers and the Department of Education have been negotiating in bad faith.
"The Minister for Education, Mr Peter Weir, wrote to schools during Halloween to break the news, echoing an announcement at the DUP conference that he was putting an additional £14m into school budgets," Mr Murphy said. "He neglected to share with his DUP colleagues, and indeed the public, that half of that money was being taken from the pockets of teachers."
Mr Murphy said INTO has not taken this step towards strike action lightly.
He added: "We are cognisant of the potential disruption further industrial action will cause for pupils and their parents but we are left with no option.
"The Department and the Employing Authorities have been exploiting teachers' goodwill for too long and we have reached a crisis point.
"We cannot stress enough how much of a crisis this is.
"The minister and the employers can still avert what will be a significant and prolonged period of industrial unrest by paying teachers what they are due for 2015/16 and engaging in genuine talks to reach a multi-year pay settlement with teachers for the remainder of this Assembly term."