Mediators at the Somali peace talks say that a "breakthrough" has been achieved, with all factions agreeing to set up a new parliament.
The talks have last more than a year but not ended the fighting
They also agreed that Somalia, which has been wracked by 13 years of fighting between rival warlords, would have a federal system of government.
A group of warlords returned to the talks on Monday and agreed to the deal.
However, a signing ceremony, which had been expected on Wednesday, has been postponed.
No new date has been set.
Kenyan Foreign Ministry official James Kiboi said that more than 20 leaders were now on board: "We have a full house. Every leader is here," he said.
More than a year of talks in Kenya has made little headway but correspondents say the international community put pressure on the Somali faction leaders to agree a peace deal.
The new parliament will be made up of 275 members, rather than 350 as previously agreed and traditional elders will be involved in selecting them, as well as warlords, reports say.
'End of anarchy'
One of Somalia's best known warlords, Hussein Mohammed Aideed, told AFP news agency: "The Somalis have agreed to settle their differences amicably by signing an agreement which will end the anarchy in Somalia."
Among those warlords who returned to the talks are Mogadishu-based Muse Sudi Yalahow and the leaders of the Juba Valley Alliance, the Rahanwein Resistance Army and the Somali National Front, which between them control much of Somalia.
Interim president Abdulkassim Salat Hassan returned to the talks earlier this month.
Last week, mediators warned that tension between the self declared republic of Somaliland the autonomous region of Puntland could threaten the talks.
Somaliland's leaders are the one group which is not party to the latest agreement.
There has also been an upsurge in fighting in recent weeks in central Somalia.