The failure to restore the Stormont powersharing institutions is a “denial of democracy”, Micheál Martin has said.
Mr Martin said he was disappointed after talks between the British government and Northern parties finished on Tuesday with no return of the Assembly before Christmas.
The Tánaiste said he could not see a reason why the Stormont Executive could not return this week.
Northern Ireland Secretary Chris Heaton-Harris has said talks with the parties over a financial package, and with the DUP over the Windsor Framework, have concluded.
But DUP leader Jeffrey Donaldson said there was still no agreement which addressed his concerns over post-Brexit trading arrangements.
Mr Martin said: “First of all, I’m very disappointed with how this has transpired. I think a lot of progress was made and there was a lot of discussion going on between the British government and the DUP in respect of the working out of the Windsor Agreement and the additional reassurances that the British government had given the DUP in respect of unfettered trade between Northern Ireland and Great Britain and vice versa.
“So, it’s very difficult to come to any conclusion as to why we don’t have the restoration of the executive and institutions this week, because it seems to me… I’m not clear what’s left to negotiate in respect of those issues.
“Fairly detailed discussions did take place between the UK government and the DUP, and then the financial package was revealed by the UK government, and the Northern parties were engaged in talks all week.”
Mr Martin said the lack of powersharing in the North was “a denial of democracy”.
He said: “It’s 18 months now since the election and the people of Northern Ireland deserve a government, and the situation is becoming very challenging fiscally, it’s becoming very challenging for the civil servants and the departments to manage health, education, housing, and so on because of the funding issues, and it’s very, very serious.
“Now, whether or not this can be brought to a conclusion in the first week of January or the second week in January remains to be seen.
“But we will be having discussions with the Secretary of State before the week is out, in the next day or two, and in that context we will be discussing next steps.
“Because the Irish Government is very concerned that because of the failure of strand one, strand two is not operating, which is the north-south bodies, which is an integral part of the Good Friday Agreement, and that’s simply not sustainable.”
He added: “My view is that the results of the election should be honoured ie, there should be a Sinn Féin first minister, DUP deputy first minister.
“I’ve a difficulty in voiding, if you like, the election result. On the other hand, we do need to look at the reform agenda.
“My ideal would have been to have the executive restored, the assembly restored, and then look at reforming it in such a way that no party could ever again have a veto on the restoration of the assembly and the restoration of an executive.
“Because in a normal situation, when an election happens, a parliament is convened and a government gets formed.
“It’s not acceptable that in this day and age we have a situation in Northern Ireland where you don’t have a parliament and you don’t have a government.”