Fianna Fáil leader Micheál Martin says that a government needs to be put together over the next number of weeks.
Negotiators from Fianna Fáil are meeting with Fine Gael today for official government formation talks.
It comes after the Fine Gael parliamentary party last week gave the green light for detailed talks with Fianna Fáil to proceed.
Deputy Martin says a majority government is urgently needed to deal with the COVID-19 crisis - but it's also important that it can be sustained beyond that.
Speaking on Newstalk Breakfast, he observed: “Consistently since the general election I’ve been of the mind that the country needs a government with a solid majority to take decisions: not just in relation to yesterday or the day before that, but even more decisions in the weeks and months ahead.
“It seems to me, just watching some of the press conferences yesterday, that the economic dimension to this isn’t fully out there yet - in the sense we don’t have an overarching framework or analysis of what will happen.
He noted: “I think over the next number of weeks we have to put a Government together.
“I don’t think the current situation is tenable either constitutionally or terms of the magnitude of the decisions that may have to be taken."
Deputy Martin is expecting the talks with Fine Gael to 'pick up pace' from today following weeks of exploratory talks and the delays caused by the coronavirus emergency.
He said: “The talks that Fianna Fáil and Fine Gael are engaging in today could form a basis for developing a programme for government."
However, he also noted there is particular urgency due to practical and constitutional issues that could arise if there is not a new government formed soon.
He explained: “Particularly if you look at the Seanad situation… we will not be able to pass legislation after this Thursday if more emergency legislation is required.
"A new Seanad can only be properly constituted when a new Taoiseach appoints 11 new nominees."