The government's stability programme leaves questions unanswered around how Fine Gael and Fianna Fáil will fund their plans over the coming years, the co-leader of the Social Democrats said.
Róisín Shortall was speaking after Finance Minister Paschal Donohoe published an update to the financial measures taken at the beginning of the Covid-19 outbreak, revealing a projected 10.5% drop in Ireland's GDP for 2020.
The Social Democrats had written to Leo Varadkar and Micheál Martin asking both to provide costings for the plans outlined in last week's policy document.
A joint letter from both leaders pledged to "borrow at reasonable costs", "reduce the deficit once the economy returns to growth" and "eliminate borrowing for current spending", but did not give specific details.
Mr Varadkar and Mr Martin are seeking a "third pillar" to form a government, with the Social Democrats, Labour and the Green Party all being approached.
However, sources within the Social Democrats say that without very clear policy commitments, particularly in relation to the provision of services, it is unlikely a programme for government would be passed by its members.
Even then, there is a feeling that many of the parties members would baulk at forming a government with Fine Gael, such is the ideological divide between the two parties.
Ms Shortall says that she and her party would need to know where that funding would come from before they could make any commitment on even beginning coalition negotiations.
"Minister Donohoe doesn't spell out the government's response to all of this. How does the government intend to get the funding required in order to pay for the Covid crisis and get the economy going again? Is he going to pursue a package similar to 2010 or is he going to pursue the idea of Eurobonds?
The Irish people had no control over this pandemic and the cost of it should not fall on their shoulders.
Ms Shortall said that she believed a commitment to public services was necessary for her party, but she did not believe Fine Gael had the same policies.
"If you look at the track record of Fine Gael, their tendency has been to privatise services. Whether that's the health service, nursing home care or indeed in relation to childcare and the lack of affordable housing. These are gaps in services have been highlighted by this crisis.
"That is where the gap is between Fine Gael and ourselves."
Ms Shortall said that her party will consider the document over the coming days and will consider a more detailed response.