Micheál Martin says he's confident a deal for a new government can be reached, but says the next few days are a 'real deadline' for the ongoing talks.
With any deal needing the approval of two-thirds of Green Party members, the Fianna Fáil leader also says it would be a 'significant crisis' if an agreement doesn't get over the line.
Fine Gael, Fianna Fáil and the Greens are continuing their talks on government formation today, with party leaders also speaking to groups of independent TDs to try to secure their support.
Speaking on The Pat Kenny Show, Deputy Martin said talks need to conclude in the coming days as the individual parties would then need to hold postal ballots to secure the backing of party members for any deal.
Asked what would happen if Green Party members rejected a deal, Deputy Martin said said: “I don’t want to speculate on what would happen after that, but I think parties would clearly have to assess the outcome of that sort of scenario.
“We have to work on the basis that each party will work to secure approval of their members once an agreement is reached… we can’t really think beyond that at this stage.
"It would represent a significant crisis, because legislation does need to be passed… action does need to be taken in terms of the economy.
"I do think you need a fully-formed government, with ministers there who know they'll be there for the next four or five years."
The Fianna Fáil leader said progress has been made in a number of areas, but challenges remain in areas such as climate change.
However, he said he's hopeful any sticking points can be resolved over the next couple of days.
He told Pat: “The key issues are economic recovery, housing, health, climate change - within climate change there are a whole range of issues that flow from that.
“The bottom line is we need a balance - there will be give and take.
"I think you can take it there will be significantly increased investment in cycling and pedestrian routes… and also there will be ongoing needs in terms of roads as well. Education is another key enabler for economic progress as well."
Elsewhere, Deputy Martin said it's his view that the country could move quicker when easing some coronavirus restrictions.
He said: “We’re told that community transmission has been well and truly controlled… ICU beds are down to 37 now. Testing and tracing capacity is the issue that I think we need further clarity on, although we are being told the capacity is there to do the requisite numbers of tests if needed.
“I do think we need to revisit the roadmap in terms of ensuring faster progress on some issues. I’ve already identified the 20 km [travel limit], for one.
“Within certain counties even it could be considered that that could be waived, because some counties have had zero [cases] for quite a number of days."
