Peter Robinson has blamed Gerry Adams for the problems he has working with Sinn Fein in Northern Ireland.
The DUP leader spoke in unprecedented detail about the difficulties he experiences working with the republican party in an interview with the Belfast Telegraph.
The First Minister claimed that Sinn Fein was unwilling to take decisions on tough issues like welfare reform because Mr Adams, its leader, was opposed to similar measures in the Dail.
He branded Mr Adams' policies as "crankery".
"It is clear that Adams believes getting support in the south is more important than getting support here in Northern Ireland.
"He believes that the south should have primacy, and that means we are unable to take sensible decisions in Government in case it conflicts with the crankery they indulge in while in opposition in the Irish Republic," Mr Robinson stated.
Mr Adams is TD for Louth and is not a member of the Assembly, but the Sinn Fein ard chomhairle, of which he is a member, has to sign off on all major decisions on Northern Ireland as well as the Republic. In the past Sinn Fein has denied that this involves any conflict.
Speaking in Belfast on Saturday, Mr Adams said the party was united in its opposition to austerity north and south.
Mr Robinson disagrees.
He told the Belfast Telegraph: "I believe that there is something of a tussle going on within Sinn Fein.
"There are those who are committed to operating within the new arrangements and the new era, but there are others who seem to want to drag us back."
He added: "This is the most difficult issue that we face. Sinn Fein is represented in Government in Northern Ireland and is in opposition in the south, and it seems to have difficulty coming to terms with the different roles that involves."
Despite these disagreements Mr Robinson believes that the power-sharing administration is secure.
"I don't think they have any inclination to move out of Government in Northern Ireland, but it is slowing down the process of decision taking to such an extent that it is not helpful in Northern Ireland," he claimed.
He added: "If you look at issues like welfare reform, education, other issues where decisions presented themselves that were obvious, that had to be taken, but they are not taking them because of the impact they might have down south."
He claimed he worked well with Martin McGuinness, the Sinn Fein Deputy First Minister, on issues where Mr Adams's input was not required.
"If you look at the areas where it doesn't conflict with Sinn Fein's agenda in the south, areas such as getting investment into Northern Ireland, we are very good at it.
"We probably are better than any of our predecessors in terms of bringing jobs into Northern Ireland" he said.
He predicted that big jobs announcements would be made in the next few weeks and that these had flowed from co-operation between Sinn Fein and the DUP.
"There are a number of very significant announcements coming and that indicates that when we work together on those kinds of issues it has a real and fruitful outcome for Northern Ireland.
"That is what makes it so debilitating that we can't get decisions taken in other areas because of the conflict between the Dail and the Assembly," Mr Robinson stated.
Yesterday, though, Sinn Fein accused the DUP of "political intransigence".
Daithi McKay, the Sinn Fein education spokesman, said the decision to block the Education and Skills Authority, which would have streamlined the province's education system, had cost the taxpayer £17 million in wasted development costs.