Sinn Féin has accused the Taoiseach Leo Varadkar of having "deliberately misled the Dáil" about an Oireachtas vote on the legal status of Project Ireland 2040.
The plan, which was launched in Sligo IT on Friday following a Cabinet meeting there, outlined plans to spend €116bn on infrastructure projects over the next 22 years.
Speaking on RTÉ's The Week In Politics, Sinn Féin TD Eoin Ó Broin said he is seeking independent legal advice on whether the plan still requires a vote in the Oireachtas before it can be put on a statutory footing.
Mr Ó Broin said: "I have written to the Chair of the [Oireachtas] Housing Committee to seek independent legal advice for our committee... so that we can have legal clarity on it."
Mr Ó Broin said: "Because if this plan doesn't have legal standing, then unfortunately of course it will just be another aspirational document...and there's no certainty it will be implemented.''
Speaking on the same programme, the Minister for Social Protection Regina Doherty rejected opposition criticism of the plan, arguing that the Dáil has voted on a motion on the plan, and will vote again.
She said: "The two largest parties in the Opposition want to talk about trivial matters around legislation... as opposed to talking about the plan."
Fianna Fáil TD Stephen Donnelly accused the Government of "by-passing any vote in the Oireachtas" and said he was concerned that Project 2040 re-enforced rather than re-balanced the growth within Dublin.