Critical talks on the future of Northern Ireland's power-sharing deal are to be held in Belfast and London.
Sinn Fein's Martin McGuinness will meet Democratic Unionist Party (DUP) leader Peter Robinson at Stormont. Gordon Brown will also meet Taoiseach (Irish prime minister) Brian Cowen at Downing Street to discuss the crisis.
Sinn Fein and the DUP are Northern Ireland's two biggest political parties. They have been at a stalemate for months over the transfer of policing and justice powers from London.
They agree that policing should be devolved, but are at odds over when this should take place.
Gerry Adams, Sinn Fein president, warned last month that if an agreement on devolving these powers was not reached, the whole power-sharing deal would be unsustainable.
Robinson said last week that republicans were creating an unnecessary political crisis, as progress was being made.
Cowen said that Britain and Ireland have a duty to help resolve the impasse. His visit is just 11 days after his last discussions with Brown.