As he travels the world, working behind the scenes and publicly to help defuse crises and push for action on issues like climate change and women's rights, Ban has also been quietly lobbying for support from the 192 U.N. member states for a second five-year term.
Egypt's U.N. Ambassador Maged Abdelaziz, whose country heads the 120-member Nonaligned Movement of mainly developing countries and China, said last month that he knew of no opposition to Ban.
"And my feeling is among the countries of the Nonaligned (Movement) that all of us are in support of his election," he told The Associated Press.
U.N. diplomats said Sunday the South Korean is expected to announce his candidacy for a second term at a news conference on Monday. Ban has scheduled the news conference to discuss his recent travels to Ivory Coast for the president's inauguration; Addis Ababa, Ethiopia, for the African Union summit; as well as to Nigeria, France and Italy. The diplomats spoke on condition of anonymity because there has been no official announcement.
Ban's spokesperson would not confirm that the U.N. chief planned to announce that he is seeking a second-term.
"During the past four-and-a-half years, the Secretary-General has been working hard to address multiple global challenges, with a strong sense of commitment and mission," said spokesperson Martin Nesirky. "He believes that when the appropriate time comes, he will be able to express his views about his future."
Once Ban makes an announcement, the U.N. Security Council must give a positive recommendation, which it would do in a resolution that needs at least nine "yes" votes and no veto by a permanent member — the U.S., Britain, France, Russia and China. The General Assembly would then elect Ban for a second term starting Jan. 1, 2012, probably by acclamation.
The diplomats, speaking on condition of anonymity because all discussions are private, said Ban's re-election could be wrapped up by the end of June.
The U.N. chief won endorsements from two former U.S. ambassadors who served during George W. Bush's presidency — John Bolton and Zalmay Khalilzad.
"I think by U.N. standards he deserves a second term," Bolton, a conservative and frequent U.N. critic, said Friday. "I think he has avoided the principal problem of his predecessor which is he has not concluded he is the secular pope. And I think that anyone who has resisted that for five years in the U.N. bureaucracy can be counted on to resist it for another five years."
Khalilzad, who said he worked very closely with Ban for almost two years, said "in very difficult circumstances he's done a good job."
"I found him to be a man with the right values to lead the United Nations," he told the AP recently. "He's committed to human rights, committed to democracy, committed to economic empowerment, focused on the plight of the disadvantaged. He's got courage. He speaks his mind. All of those are values that I think are important for a secretary-general."
But Ban also has been criticized for his low-key style, his lack of charisma, and his failure to criticize human rights abuses in powerful countries, especially China and Russia.
Human Rights Watch was very critical of Ban for failing to raise China's rights record or its imprisoned Nobel Peace Prize laureate Liu Xiaobo in a meeting with President Hu Jintao last November, and for not speaking out against abuses in Myanmar and Sri Lanka. Ban insists he has spoken out for human rights.
"We certainly recognize that in recent months, he has been much more vocal against human rights abuses in Egypt, in Libya, in Ivory Coast," Philippe Bolopion, U.N. director for Human Rights Watch, told the AP on Friday.
"We hope that in his second mandate he will use the moral authority of his office in a more consistent manner, regardless of the political implications or the sensibilities of the five permanent members of the Security Council," Bolopion said.
Tim Wirth, president of the United Nations Foundation which was started to administer Ted Turner's $1 billion pledge to the U.N., said
"Ban Ki-moon will be re-elected — there's no doubt about it."
"The question now is, what's the agenda for the second term and how can this be aggressively pursued?" he said.
When Ban took over the helm of the U.N. from Kofi Annan, he called himself "a harmonizer and bridge-builder" and promised to restore the world body's tarnished reputation and push for peace in the Middle East and Sudan's conflict-wracked Darfur region.
The former South Korean foreign minister and career diplomat, who turns 67 on June 13, put climate change at the top of his agenda and said he would mobilize world leaders to take urgent action to combat it. And he promised to strengthen the three pillars of the United Nations: security, development, and human rights.
Wirth, a former U.S. senator from Colorado, said the secretary-general has done "an extraordinary job of elevating the climate issue to the top of the agenda" and has made "a very deep commitment" to women with the establishment of a new agency, UN Women, headed by former Chilean President Michelle Bachelet.
But peace in the Middle East and Darfur remain elusive and so does a climate change deal. In addition, there are new issues to tackle including uprisings across the Arab world and the continuing fallout from the global economic crisis including unemployment and poverty.
Khalilzad, Bolton and Wirth agreed that Ban must do more in his second term to reform the U.N. bureaucracy.
One example, Khalilzad said, is the more than 9,000 mandates that the U.N. has to fulfill. Many are outdated and consume resources that could be used to deal with issues of current importance, he said.
As for the secretary-general lacking charisma, Wirth said that usually diplomats "are people who are very quiet, competently doing the job day in and day out, and Ban Ki-moon is certainly one of those, and he's the hardest working person I've ever known in my life."