The majority of the parties are expected to agree on the compromise rules, hammered out under the chairman, former United States Senator George Mitchell, despite last-minute objections from both the Democratic Unionist Party and unionists in the UK.
The parties at Stormont will then consider the agenda for substantive talks, including decommissioning of weapons and the province's constitutional status. The DUP has threatened to walk out if this last matter is discussed. The party also questions the right of the nationalist Social and Democratic Labour Party to stay in the talks after pulling out of the Northern Ireland Forum on Friday.
The parties may agree to extend sessions by two days to Thursday before adjourning for a month's summer break. Sources close to the talks dismissed suggestions that Mr Mitchell is threatening to resign soon as chairman. One said: "The timing doesn't make sense now there are signs of some agreement and he's no quitter."