Fine Gael and Fianna Fáil have sent what was termed a "comprehensive" letter to the Green Party this evening seeking to answer the 17 questions posed by the Greens last week.
Fine Gael and Fianna Fáil have 72 seats between them, but a majority of 80 is needed to form a government.
They are hoping to entice smaller parties, including the Green Party, the Labour Party and the Social Democrats, to increase their Dáil numbers.
The Green Party has 12 seats, Labour has six, the Social Democrats has six and there are 19 Independent TDs.
Tonight's correspondence with the Green Party is likely to pave the way for a meeting in the coming days between party leaders Eamon Ryan, Micheál Martin and Leo Varadkar.
Separately, the Labour Party posed five questions for Fianna Fáil and Fine Gael, and outlined 21 principles, in a two-page document on government formation today.
The letter is addressed to Fianna Fáil leader Micheál Martin and Fine Gael leader Leo Varadkar and forms a response to a joint policy document agreed by the two parties earlier this month.
Among the questions posed by the Labour Party are:
- How much are you prepared to borrow in 2020, 2021 and 2022 respectively to maintain public services and secure additional investment?
- What taxation measures are you prepared to consider, and how do you propose to guarantee that you can implement a radical programme for government over the next five years without increases in taxation for higher earners?
- What cuts to departments and agencies, relative to the allocations made in the 2020 Estimates have you considered?
- Will you honour the current public sector pay deal, and what is your approach to negotiating a follow-on agreement, including equality of pay and conditions for our Defence Forces?
- Will you commit that the Covid-19 pandemic unemployment payment will continue at the current rate for workers who have lost their jobs in affected sectors?
Labour leader Alan Kelly said an "understanding" of Mr Martin and Mr Varadkar's budgetary approach would "provide the Labour Party with the framework to consider the compatibility of our vision for Ireland's future, with what you have propose to date".
In a supplementary question, and focused on the make-up of any coalition, Mr Kelly said the Labour Party's six TDs would not provide Fianna Fáil and Fine Gael with a majority government
He said he is seeking "clarification on how you believe a stable Dáil majority might be achieved."
Last week, two groups of Independents met a joint Fianna Fáil and Fine Gael negotiating team.
However, the Regional Group has now told those parties that they are waiting for clarity on the Green party position before committing to any further talks.
It is understood that the Independent Group, which includes TDs Marian Harkin, Michael Fitzmaurice and Michael McNamara, is also going to seek further detail on the Greens' policy plans.
Additional reporting: Paul Cunningham