FIANNA Fáil leader Micheál Martin has urged the British and Irish governments to directly intervene to end the "stranglehold" in Stormont.
He also called for an overhaul in the north-south bodies set up under the Good Friday Agreement.
Speaking yesterday at his party's annual Easter Rising commemoration, Mr Martin attacked the DUP/Sinn Féin-led adminstration for wreaking "immense damage" on Northern Ireland's post-peace process institutions.
"We need direct engagement by both the Irish and British governments to end the stranglehold in Stormont by two parties," he said.
"This is doing immense damage to public support for the institutions and public engagement in politics."
Mr Martin has previously accused the DUP and Sinn Féin of pandering only to their own communities while failing to build bridges between them.
Pointing out his own party's "central role" in the 1998 peace accord, Mr Martin said the Good Friday Agreement provided an opportunity to build "not just an absence of war but also lasting reconciliation and development".
"This opportunity is being wasted," he said during the 1916 commemoration at Dublin's Arbour Hill.
"We need a new beginning in the concept of north-south bodies, which have an enormous potential to deliver services and sustained development on both sides of the border."
The north-south bodies include Waterways Ireland, Food Safety Promotion Board, Trade and Business Development Body (known as InterTrade Ireland), Special EU Programmes Body, North/South Language Body, Foyle Carlingford and Irish Lights Commission and Tourism Ireland.
Mr Martin also declared during his speech that the Republic is on the cusp of a more complex style of government that strips absolute power from leaders.
Ahead of crunch talks resuming this week between his party and Fine Gael on a new minority administration, Mr Martin said the days of majority rule are over.
"I hope that we will shortly be able to move our politics on to a more inclusive and consensual approach," he said.
"No one in Dáil Éireann will be able to dominate decisions – and this is a good thing."
The Fianna Fáil leader attacked the arrogance of the outgoing Fine Gael/Labour coalition.
Mr Martin said the unprecedented voter schism after February's general election meant the old political system was now "broken and cannot continue".
"The idea that you can only govern if you can control everything which happens in the Oireachtas is completely discredited," he said.
"We need a politics which respects important differences between parties and groups and requires a much deeper engagement on substance.
"This works well in many countries and it can work here if people are willing to try."
