Editor's note: Jimmy Carter was the 39th president of the United States.
Juba, Sudan (CNN) -- On Sunday, the people of Southern Sudan began casting ballots in a historic seven-day referendum in which they will choose between continued unity with northern Sudan, or secession to become a new state.
While a successful referendum now appears likely, the Sudanese must confront a host of critical problems to ensure sustainable peace and development. To facilitate this, the United States and key international actors including the African Union, the United Nations, the Arab League and others in the region must remain actively engaged and offer critical support.
As part of the Carter Center's 100-plus-person observation team in Sudan, I witnessed massive turnout at the opening of the polls in the southern capital of Juba and an outpouring of heartfelt celebration.
Earlier, there were widespread fears about the potential for violent conflict and a possible rejection of the process by the Sudanese government in Khartoum. However, the atmosphere improved dramatically in recent weeks. Leaders in both the North and South have taken positive steps, including a speech in Juba by President Omar al-Bashir in which he said that the Sudanese government will accept the outcome, and will celebrate the results together with the people of Southern Sudan, regardless of their choice.
The referendum on self-determination is one of the key steps in the 2005 Comprehensive Peace Agreement, or CPA, which ended a 22-year civil war that caused more than 2 million deaths and displaced 4 million. For decades before and during the war, the people of Southern Sudan demanded the right to determine their political future in an open democratic process. Although the official referendum results might not be known until early February, a vote for secession is widely assumed.
The CPA was intended to commit the governments in the North and South to make the prospect of continued unity an attractive option, and to democratize their societies. Unfortunately, there has been little progress in these areas. Relations between the North and South were mostly strained, and the elections held last April were seriously marred by manipulation and coercion in both regions of the country.
In the event of a vote for secession, Sudanese leaders will need to resolve a series of critical issues to manage a peaceful separation into two states and to create a strong foundation for friendly and prosperous bilateral relations.
In spite of their differences, there are many ties that bind their closely integrated societies together. They are destined to share their lives/common futures in the porous border regions, which encompass roughly one-third of the total population of Sudan.
Key challenges include demarcating final borders, resolving citizenship issues, building a framework for economic cooperation and managing the division of revenue from oil, most of which is currently extracted from fields in the South, but refined and pumped through pipelines crossing the North for export via Port Sudan on the Red Sea. An especially critical problem concerns the disputed oil-rich border area of Abyei, which remains unresolved and a source of much tension.
On these and other issues, the international community should assist both sides to reach acceptable agreements and to manage the difficult political and economic changes they must undergo. Further, in the event of a successful referendum and continued good will to resolve tough issues, the United States should resume normal relations with the government in Khartoum and support debt relief for the governments in both the North and South. In addition to the loss of one-third of its geographic area, the economic cost to the North of losing a large share of current oil revenues will hurt the economy significantly.
Regardless of the outcome of the referendum, the leaders in both the North and South must demonstrate a serious commitment to building genuine democracies. The ruling party in the South recently formed a broad-based political council to meet after the referendum and chart a course for an inclusive transitional government, a new constitution, a constitutional assembly and new elections.
In the North, the government needs similar reforms to accommodate interests of a broad range of civil society and opposition parties. Khartoum should explore ways to improve relations between the center and the outlying ethnically diverse areas, especially in locations far from Khartoum, including in South Kordofan, Blue Nile and Darfur. A final resolution of the Darfur conflict is essential for Sudan to have lasting peace.
After the referendum, Sudan's friends and neighbors should continue to help the Sudanese to build lasting peace and prosperity in the region.
The opinions expressed in this commentary are solely those of Jimmy Carter.