A government led by Fine Gael and Fianna Fáil does not represent the change that people voted for, Sinn Féin leader Mary Lou McDonald has claimed.
Ms McDonald set out her stall as de facto leader of the Opposition as members of Fine Gael, Fianna Fáil and the Green Party prepare to decide whether to approve the Programme for Government.
The Sinn Féin leader claimed the agreement was an attempt to deny change, protect the status quo and "to continue with the same broken politics that has so badly failed workers and families".
She argued the agreement wasn't the only deal possible and insisted the "chance to form a government of change is real".
Sinn Féin won 37 seats at the General Election, its highest ever. Ms McDonald said Taoiseach Leo Varadkar and Fianna Fáil leader Micheál Martin set out to exclude Sinn Féin and "in doing so they excluded the demand for change coming from the people".
She added: "Grassroots members of the Green Party know this. Grassroots members of Fianna Fáil also know this."
Both Mr Varadkar and Mr Martin ruled out going into government with Sinn Féin before the election citing differences in economic policies and the party's association with the Provisional IRA.
After the election, Mr Martin told the Dáil he couldn't go into coalition with Sinn Féin because of its "efforts to legitimise a murderous sectarian campaign". Ms McDonald responded at the time saying she "did not care" what he thinks about her party.
Ms McDonald last night said: "No matter what happens workers and families must not be the ones to shoulder the pain of the economic crisis." She warned: "There can be no return to austerity."
She said people were "impatient for change" and Sinn Féin had the policies to "deliver a fresh start", listing proposals to set the pension age at 65, create a single-tier health service and provide affordable housing.
She added: "Sinn Féin will defend the change that the people voted for."
Elsewhere, Labour Leader Alan Kelly claimed the Programme for Government "failed to grasp the potential to dramatically improve healthcare, education, childcare and housing" in the midst of a global pandemic that had shown the essential role of the State in providing public services.
He welcomed the environmental concessions made to the Green Party but claimed the document was "full of re-branded and repackaged commitments" with language left "deliberately vague".
Social Democrats co-leader Róisín Shortall said the programme had "a lot of good aspirations but there were no indications of any time-lines or indeed any indication of how it's going to be funded".
She claimed this meant it was unlikely the measures in the document would be delivered. Ms Shortall argued "funding is kicked down the road with a promise of an economic plan further in the year".
She said the Government's intentions for borrowing and attitude to deficit must be known now. She added that the Social Democrats would support "any and all measures which we believe will improve Irish society".
Rise TD Paul Murphy claimed the Programme for Government was a "trap" for the Green Party.
He argued that it contained "vague talk of change to lure the Greens in to be a green mudguard for austerity".
The Dublin South-West TD urged the Green Party's grassroots members to reject the deal.