Sinn Féin claims the Government has 'failed spectacularly' to keep hold of Ireland's 12.5% corporate tax rate.
Ireland is expected to agree to a minimum global corporate tax rate, following a Cabinet meeting on Thursday.
Around 130 countries have pledged to support the plan, with Ireland one of the few nations not signed up.
An updated draft of the OECD proposal has dropped the wording 'at least' from a rate of 15%.
It is thought this opens the way for Ireland to become party to the deal.
Last week, Finance Minister Paschal Donohoe told Newstalk the Government was to "review where we stand" on the tax plan.
He said talks were continuing to see if progress was possible - including with finance ministers from the US, UK, France, Germany and Japan.
Sinn Féin's finance spokesperson Pearse Doherty told Newstalk Breakfast Ireland was unlikely to win this on its own.
"I think, to be fair, the odds were stacked against us from the get-go in relation to this.
"Some of that is the result of our own, or the Government's own, allowance of aggressive tax planning in our code.
"But let's be clear: the Government's objective here was to secure the 12.5% tax rate within the OECD framework, after the 130 countries agreed in principle to the 15% rate.
"On that measurement, there's no doubt about it: we failed and failed spectacularly".
Deputy Doherty says while he believes Minister Donohoe's attempts were genuine, Ireland had few who supported our position.
"I believe he was genuine in relation to trying to secure the 12.5% rate within the OECD framework.
"I think the decision to opt out from that point actually obviously caused more reputational damage.
"But the reason why we have no friends here at an international level is that aggressive tax planning has happened.
"It's happened on successive Irish government watch's.
"And the question is if we actually applied an effective 12.5% rate - which is where companies would actually pay 12.5%, which most of the companies in Ireland do.
"But the problem is is those minority of large companies that were able to write-down their tax liability to close to zero has caused us immense reputational damage, and therefore we have very little friends at an international level".
But he says he is hopeful a dual system - which would see smaller, domestic firms pay less corporate tax - is possible.
"We expect that the Commission would grant that, but it's not certain. The 12.5% rate needs to stay for those companies".