Northern Ireland leaders are to travel to the United States today amid doubts over the stability of power sharing arrangements.
First Minister Peter Robinson and Deputy First Minister Martin McGuinness have a number scheduled meetings with business leaders in New York.
However, doubts remain about the stability of power sharing arrangements at Stormont due to a disagreement about welfare reform proposals.
Mr McGuinness said an additional £200m was required to resolve the row.
Speaking on RTÉ's Morning Ireland, Mr McGuinness said that figures provided by the Department of Social Development showed that apart from the £125m that has been promised in the deal, a further £200m was needed "to protect the most vulnerable in our society".
He insisted the deal struck at Stormont last December protected payments made to present and future recipients of welfare in several categories.
The DUP leader said there is an agreed budget line of over £125 million in a pot of over £500m, and Sinn Féin's demand would require finding an additional £300m over the next six years.
One possible solution would be identifying such resources elsewhere in Stormont's finances.
However, that would involve raiding some other departmental budget line, which may be difficult given the public element of the disagreement.
Taoiseach Enda Kenny has said he hoped the parties can work out the issues that separate them.
