Tue Nov 3, 2:02 PM ET
Sudan is due to hold its first presidential, parliamentary and regional elections in 24 years in April and voter registration began on Sunday.
But the southern former rebel Sudan People's Liberation Movement (SPLM) has been boycotting parliament until the National Congress Party (NCP) of President Omar al-Beshir agrees to enact promised security reforms and resolves the row over the 2011 referendum.
"It?s a difficult and lengthy process, but failure is not an option," Gration said.
"Both the national elections and the referendum on self-determination in southern Sudan are only months, not years, away.
"Obviously we want to see progress and we are working to get this."
Sudan's Foreign Minister Deng Alor said most south Sudanese would choose independence if the referendum were held now.
Only a "miracle" can make unity attractive for southerners before they vote in 2011 on whether to break away, said Alor, a former rebel fighter and still a senior SPLM official.
"If southerners were asked now they would overwhelmingly vote for separation," he told journalists on Tuesday.
Southern Vice President Riek Machar held talks late on Monday with Second Vice President Ali Osman Taha and the two men were due to meet again on Tuesday.
But Machar's office described the atmosphere of the talks as "not friendly."
The two sides are at loggerheads over the quorum that will be required for the 2011 independence referendum to be valid, a row that has intensified since southern leader Salva Kiir openly called on Saturday for the south to break away.
The NCP is insisting on a minimum two-thirds turnout for the outcome to be binding. The SPLM is demanding a lower figure.
"The SPLM ... called the NCP to meet somewhere between 50 percent and 66 percent for turnout quorum. But the NCP is adamantly refusing to move an inch below the 66 percent," Machar's office said.
"In an effort to bring the two sides together, General Gration asked both sides to abandon their positions and meet somewhere between 62 percent and 66 percent for the turnout," it added.
The promised independence referendum is the centrepiece of a 2005 peace deal between the SPLM and the NCP that brought an end to Africa's longest-running civil war.
The deal provided for a six-year interim period ahead of the vote in which the two sides would share power in Khartoum and the south would enjoy regional autonomy.
( What's this? )