A parents' representative who once labelled teachers "terrorists" has had a proposal to invite her to the ASTI's annual conference rejected by the union's leadership.
It is understood the move, aimed at ending the tensions which exist between the ASTI and the Catholic Secondary Parents' Association (CSPA) following the comment by its spokeswoman, Ms Barbara Johnston, was vetoed by a large majority of the ASTI's standing committee last week.
One source at the meeting said: "There is still a deep feeling of hurt out there over that particular comment...but there is no animosity between teachers and parents."
Ms Johnston wrote in The Irish Times three years ago that instead of acting like professionals, teachers were "behaving like terrorists" in their pay dispute with the Department of Education.
However, several meetings in recent months between the ASTI and the CSPA had given rise to the hope that a line could be drawn under the affair.
The ASTI leadership's refusal to invite Ms Johnston comes at a time when all three teaching unions have expressed their anger at plans by the Minister for Education, Mr Dempsey, not to accept an invitation to their conferences.
In a letter to the ASTI, the CSPA admits that while the words used by Ms Johnston were "not the best-considered words ever put on paper", it would "continue to maintain that they were in keeping with the language of the day.
"On March 10th, 2001, a spokesperson for the ASTI informed the Irish nation that teachers were now ready to launch their nuclear weapon at the Irish education system," the letter states.
"This statement, and the war-faring language it was delivered with, shocked parents....many parents were devastated and appalled."
Over the past two years, the CSPA had initiated a number of meetings with members of ASTI, the letter continues.
"These meetings have been positive....The CSPA hopes that if parents are able to move past what should be left in the past, then teachers will too."
Meanwhile, the president of the ASTI, Mr Pat Cahill, has confirmed his interest in replacing Mr Charlie Lennon as general secretary of the union.
Mr Cahill is described by one senior source as a popular figure who is not afraid to promote debate within the ASTI.
However, it is understood that Mr John White, who was appointed acting general secretary last weekend, is still the clear favourite to take over the role which pays €100,000 a year.