In doing so, Washington has pledged to assist the country and review its status as a "sponsor of terrorism".
"I am optimistic that they will do it in time before the end of the year," senior US government official told journalists in Nairobi on Friday, a day before Sudanese Vice President Ali Usman Taha and Sudan People's Liberation Army (SPLA) chief John Garang resume talks in the Kenyan town of Naivasha.
"We are hoping that the cake is made, all they need to do is put on sugar icing. We are very close to peace," the official, who requested anonymity, added.
"They could finish this agreement in terms of a global agreement by the end of this session, which ends on 19 December, and in January literally wrap up the details and the technical matters," he said.
Delegates from both sides have been meeting in Naivasha for the past week to thrash out the remaining three sticking points: power and wealth-sharing and the status of the three disputed areas of Abyei, Nuba Mountains and Southern Blue Nile.
"The remaining sticking points I think will be overcome because the parties have gone so far towards making this agreement. It is almost inevitable that all will not go to waste," he said.
"We are hoping that the cake is made, all they need to do is put on sugar icing"
The official said Washington was waiting for a final peace accord so that it could pool funds to help the war-ravaged country.
"In the United States, we are moving close to the time when we are putting serious money on the table, we need to have a settlement pretty soon... it is a reality that the ability to put in a large sum of money depends on the time," the official said.
He explained that if an agreement came in February or March it could limit US ability to raise enough cash.
The US could give as much as $200 million a year, the official hinted, adding that Washington is waiting "to do some things for the (Sudan) government... before they go into real African politics."
The European Union has pledged about $300 million, he added.
Asked if the US could consider revising its list of countries that "support terrorism", of which Sudan is one, the official responded: "We have to assess it, first we need a peace agreement to do so, because there will be a new government in place and old things may soon fade away."
"This is really a test of political partnership between the parties (Khartoum and SPLA). They can come up with compromises, they will prove that they can work together in the future," he added.
Since it erupted in 1983, more than 1.5 million people have died in Sudan's multi-faceted civil war, which pits Khartoum's hardline Islamic regime in the north against southern SPLA rebels and other armed opposition groups.