The basis cited by SIPTU for next week's threatened public transport strike was undermined last night by the leader of the other main union in CIÉ.
Opening the biennial conference of the National Bus and Rail Union in Galway, Mr Liam Tobin did not comment directly on SIPTU's decision to call the strike next Thursday.
He made it clear, however, that the NBRU believes progress is being made in talks with the Department of Transport on the future of the Dublin bus market.
The "lack of meaningful progress" in the talks was cited by SIPTU this week as the main reason for its planned 24-hour stoppage on the day after the St Patrick's Day holiday.
All Iarnród Éireann, Bus Éireann and Dublin Bus services are likely to be shut down for the day if the strike goes ahead.
SIPTU also plans a six-hour stoppage at Dublin, Cork and Shannon Airports from 7.30 a.m. on the same day. About 25,000 intending passengers face flight delays or cancellations.
That action is also in protest at what the union says is the lack of progress in separate talks with the Department on the future of Aer Rianta.
If SIPTU members go ahead with the action in CIÉ, they are likely to be supported on the ground by colleagues in the NBRU.
In his address to the conference as NBRU general secretary, however, Mr Tobin said his union would be continuing talks with the Department on the day the strike is to take place.
Unions are opposed to plans by the Minister for Transport, Mr Brennan, to break up CIÉ and franchise out 25 per cent of Dublin Bus's routes to private operators.
The two sides recently entered discussions on the issue under the chairmanship of Mr Kevin Foley of the Labour Relations Commission.
"I don't want to give any hostages to fortune, but the talks currently under way have been far more positive than any previous talks during Mr Brennan's term of office," Mr Tobin told delegates.
The discussions would continue on March 18th and 19th, "at which time we expect further progress to be made".
The Department knew that the NBRU was prepared to "fight them all the way if necessary", but also that it was equally ready to negotiate a good deal for its members and the travelling public, Mr Tobin said.
"I believe that with goodwill on both sides we can reach a positive outcome to these talks and if we don't it will not be for want of trying on our part."