With more than 600 second-level schools expected to close today, the Government is under intense pressure to bring forward a new pay review body which could deliver substantial pay rises for teachers.
The Cabinet is expected to discuss the issue today as classes for some 350,000 pupils are cancelled and 16,000 teachers mount pickets around the State.
The Association of Secondary Teachers, Ireland (ASTI) said industrial action was the only way it could pursue its 30 per cent pay claim. However, the Taoiseach, Mr Ahern, said the only way forward was through the national pay deal.
The union has claimed 64 per cent of the public is behind its action.
Today's strike will be followed by six days of supervision withdrawal and another one-day strike early next month. The ASTI has warned that the dispute could then escalate.
The most serious option it is considering is withdrawing from the State examinations.
No new initiative is expected to come from the Cabinet meeting. However, senior sources said a proposal to bring forward a new pay review, set up under the Programme for Prosperity and Fairness (PPF), was being explored in Government circles.
Under the plan, the benchmarking review body, which links public service pay to that of the private sector, would be fast-tracked. The review body could reward teachers for changes in productivity or for taking on new responsibilities.
The body was due to report in June 2002 but the Government is coming under increasing pressure from the other teaching unions - the Irish National Teachers' Organisation and the Teachers' Union of Ireland - to bring this forward to June.
In a further effort to break the deadlock in the ASTI dispute, the Government may also invite the union to attend the first meeting between public service unions and the benchmarking body next week.
Asked what he thought of today's strike, Mr Ahern, on RTE radio, said: "The Government has no interest in starting a war with anyone, least of all these children's teachers. We are not interested in doing that."
However, he said he was disappointed the action was going ahead.
The ASTI said it still hoped for meaningful discussions with the Government. It said teachers did not want to take the action but had no choice.
ASTI is the only teaching union outside the PPF and its executive has also rejected benchmarking.
Despite this, one Government source said: "We need to help ASTI climb out of the hole they have dug for themselves . . . Benchmarking is the way to sort out their dispute."
The Government is also under pressure from the TUI which has 10,000 members and which traditionally takes a harder line on pay than the ASTI. It will ballot shortly on industrial action after the Government refused to bring forward the benchmarking process and failed, in the union's view, to compensate members for inflation.
If the Government fails to make a move on benchmarking, the INTO could also begin industrial action.
As the benchmarking process is designed for the entire public sector, there is some concern in Government that any special timetable for teachers could create knock-on problems with other public service unions.
However, there is also an increasing recognition it could help to halt a protracted and bitter dispute with the ASTI.
The National Youth Council has said students doing exams would be put under particular pressure.
"Students have enough to deal with in preparing for exams without having to deal with industrial action by teachers," said its president, Mr James Doorley.