A TD has called for the privatisation of bus routes to be frozen for five years.
It comes after the National Transport Authority gave notice of its intention to put a number of Bus Eireann routes out to tender.
Unions have hit out at the plans saying they may undermine workers' rights.
Fianna Fáil's Transport Spokesman Robert Troy wants it stopped.
Mr Troy said: "What we want to see happening is, effectively, a pause button being pressed and no further privatisation of any additional routes for a minimum of five years until we get a full picture.
"What we'd also like to see the Government do is get real about public transport and have a significant investment in public transport."
Deputy Troy has called for an open and transparent analysis of the impacts of privatisation on bus services.
He said: “I am very concerned by the fact that the NTA have unchecked powers when it comes to privatising further bus routes. The buck stops with Minister Ross and yet he is standing idly by as this happens.
"The effectiveness of privatisation can only be assessed after it has commenced and a period of consultation has occurred. We cannot have a situation whereby privatisation that is proving inadequate is allowed to continue.
"I have introduced the Dublin Transport Authority (Amendment) Bill 2018, which is currently before the Dáil. The Bill is designed to prevent any additional privatisation of routes pending a comprehensive review of the routes which have been privatised to date."