Fianna Fáil leader Micheál Martin has claimed Sinn Féin is not fit for government in the South and has angrily rejected a call from the Derry Ard Fheis for guarantees on a border poll.
Deputy Martin attacked Sinn Féin after the party's Sligo-Leitrim T.D. Martin Kenny said Fianna Fáil were out of step on the question of the reunification of the country.
"The reality is that the Taoiseach and people in Fianna Fáil are simply out of step with public debate on Irish unity. They both continue to frame the debate in terms of what will be lost instead of what is to be gained," said Deputy Kenny.
The Fianna Fáil leader said he had been surprised a guarantee on a border poll had been demanded as a requirement for any future government partner at the Sinn Féin Ard Fheis in Derry.
And he claimed that Sinn Féin were not fit for office in the South because the party's "demands took the place of engagement and persuasion".
However, he said they should get back to government in the North.
"We have been referenced by the Sinn Féin spokesman today. It is surprising to say the least that at the conference in Derry, Sinn Féin announced that it would set as a precondition for entering Government in the Republic being given cast-iron assurances about the holding of a unity poll," he said.
"When one takes that in tandem with the book Burned: The Inside Story of the 'Cash-for-Ash' Scandal and Northern Ireland's Secretive New Elite, the definitive work on the cash for ash scandal in the North, and its revelation that the Sinn Féin Minister for Finance in the North had to seek the authority of non-elected Ard Chomhairle officials [sic] of Sinn Féin - Ted Howell and Pádraic Wilson - before he could cease the scheme, it reinforces the fact that Sinn Féin is unfit to be in government established under Bunreacht na hÉireann because its own party demands take the place of engagement and persuasion," he told the Dáil.
Mr. Martin said the decision to collapse the power-sharing institutions in Belfast had been anti-democratic.
"I would put it to the Taoiseach that for Sinn Féin, it is a legitimate tactic to collapse democratic institutions until it gets its own way. I ask people to read Burned: The Inside Story of the 'Cash-for-Ash' Scandal and Northern Ireland's Secretive New Elite and also to look at the fact that in a recent election within Sinn Féin, the challenger was disappeared from public view and was not allowed to make his case.
"That is not democratic. Anyone genuinely interested in the unity of the people of this island should be trying to get the agreed institutions of the peace settlement to work and to show those opposed to Irish unity that they share a community of interest. How does collapsing the Assembly and Executive advance Irish unity? It was deliberately collapsed by Sinn Féin," he said.
But while he said he believed Sinn Féin were unfit to govern in the South under the terms of the Irish Constitution he called for them to return to government in the North.
"Does the Taoiseach agree that what we need today is an end to the politics of collapsing democratic institutions and a return of the democratic Assembly and Executive in Northern Ireland? I met people in Newry recently who cannot understand why it has been collapsed.
"Only when this is done can we return to engagement, without which the union of peoples on this island is impossible. It is about persuasion, not dividing people," Mr. Martin told the Dáil.