Peter Robinson and Martin McGuinness are in London to hold more budget talks with the Prime Minister.
The First and Deputy First Minister will meet Gordon Brown to break the stalemate over the devolution of policing and justice powers.
Discussions were held last week at Downing Street, no figures were agreed but both ministers said progress had been made.
It is understood the issue of equal pay was a sticking point.
Earlier Mr McGuinness said it was important for the DUP and Sinn Fein to reach a deal now as there will not be a better one in the future.
The two men had been expected to ask Mr Brown if he was prepared to fund a budget shortfall estimated to be about £600m.
© UTV News