The secondary teachers’ union, ASTI, has rejected the pay equality deal for new entrants.
The union voted the proposal down on a margin of 53-47.
The ASTI is the second teachers’ union to vote “no” - and by a similar margin as the primary teachers’ union, the INTO.
The third teachers’ union, the TUI, voted 53-47 in favour.
The turnout in the ASTI ballot was 58pc and the union executive will meet shortly to consider the outcome.
The INTO is currently consulting with its members in the lead up to a ballot on industrial action.
The nurses union, the INMO has also voted against the proposals and is currently balloting its members on industrial action.
Unions that take industrial action in pursuit of a better deal have been warned that all members will suffer pay penalties, including delays in the payment of increments and post-austerity pay restoration.
While the pay equality proposals go a long way to bridging the gap between public servants recruited since 2011 and longer-serving colleagues, they did not restore parity for all.
ASTI president Breda Lynch said union members were firmly committed to achieving equal pay for their lower paid colleagues:
She said ASTI members remained steadfast in their determination to achieve justice for their lower paid colleagues – that is, equal pay for equal work.
Ms Lynch recalled that, in 2016, the ASTI took strike action over the discriminatory pay of post-2010 teachers, as a result of which ASTI members suffered penalties.
“However, their action put unequal pay firmly on the agenda, making it an issue the Government could no longer ignore. Despite this, this latest proposal from the Government represents insufficient progress and does not achieve equal pay. We will continue to pursue the full restoration of pay for our lower paid colleagues.”