Under the Good Friday Agreement, properly known as the Belfast Agreement, voters elected a new Northern Ireland Assembly to form a parliament. Every party that reaches a specific level of support gains the right to name members of its party to government and claim one or more ministries. Ulster Unionist party leader David Trimble became First Minister of Northern Ireland. The Deputy Leader of the SDLP, Seamus Mallon, became Deputy First Minister of Northern Ireland, though his party's new leader, Mark Durkan, subsequently replaced him. The Ulster Unionists, Social Democratic and Labour Party, Sinn Féin and the Democratic Unionist Party each had ministers by right in the power-sharing assembly.