Former minister for transport Séamus Brennan, who set up a group to study the feasibility of a north-south rail corridor in the west, said yesterday that he will continue to support the concept in Cabinet, but he believes it may only happen in a piecemeal way.
The study group established by Mr Brennan is expected to submit a report to the Government within weeks.
Mr Brennan, who is now Minister for Social and Family Affairs, said he would be surprised if the group wasn't thinking the best way of opening up a service between Sligo and Limerick was "in a modular way".
"I don't see anybody coming in on a Monday morning and announcing the building of the entire line from north to south."
The Minister's view is bound to disappoint groups campaigning for a western rail corridor.
It also clashes with Fine Gael leader Enda Kenny's Dáil claim four weeks ago that engineers believed the line could be completed within two years.
Mr Brennan said: "I did ask the working group to be hard-headed and practical, but also to have a vision that one day we will have a western rail corridor up and running.
"We have to put it together in a piecemeal way as and when we can. My personal position is that I am strongly interested and will encourage its development."