UNITED NATIONS (AP) ― Secretary-General Ban Ki-moon announced Monday that he will seek a second term as head of the United Nations, pledging to keep leading the world body as a “bridge-builder” at a time of unprecedented global change. His re-election is virtually assured.

The former South Korean foreign minister finally made public what has been the U.N.’s worst kept secret ― that he wants a second term ― at a news conference to discuss his recent trips to Europe and Africa. In his virtually non-stop travels around the globe, he has been quietly lobbying world leaders for support.

Ban said he had sent letters to the 15-member Security Council and 192-member General Assembly “humbly” offering himself for consideration for a second five-year term. His current term ends Dec. 31.

“During the past 4 1/2 years, we have undertaken important work and found common ground on critical global issues of peace and security ― from Somalia to Sudan, Ivory Coast to Afghanistan, Iraq and the Middle East and far beyond,” Ban said in the letter to the council obtained by AP.

“I am proud of all we have done together, even as I am mindful of the formidable challenges ahead,” he said. “It would be an honor to have the opportunity to continue serving in this great and noble endeavor.”

Though he insisted he takes nothing for granted, Ban has no opponents and diplomats say he has the backing of the five veto-wielding members of the Security Council ― the U.S., China, Russia, France and Britain ― who must recommend him. He likely has support from the entire General Assembly, which will probably elect him by acclamation later this month.

The Security Council met privately late Monday afternoon to discuss how to proceed. In the past, the council has adopted a resolution recommending a candidate for the U.N.’s top job.

Ban won immediate endorsement for his candidacy at a breakfast Monday with the 53-member Asian Group. He said he plans to meet with the U.N.’s other regional groups, from Africa, Latin America and the Caribbean, Eastern Europe, and mainly Western nations, in the next two days to discuss his candidacy.

French Foreign Minister Alain Juppe quickly welcomed Ban’s announcement.

“He has shown courage and determination during a time of crisis,” Juppe said in a statement. “We have no doubt that he will show those same qualities during a second term at the head of the U.N.”

China’s U.N. Ambassador Li Baodong said the Asian Group supports Ban because he has led the U.N. though “stormy weather and troubled water” and enabled the organization to play a “more important role” in peace, development and international affairs.

The secretary-general “has demonstrated strong leadership, is a person of action, and is a person with vision for better world and better U.N.,” Li told reporters.

Russia’s U.N. Ambassador Vitaly Churkin said Moscow supported Ban for a second term.

U.S. State Department spokesman Mark Toner welcomed Ban’s announcement but wouldn’t say whether the Obama administration backed him for a second term. He added that the U.S. will have more to say in the coming days.

Ban, who will turn 67 on June 13, 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.

But he has won praise for putting climate change at the top of his agenda, for his commitment to women and nuclear disarmament, and for his recent strong support for pro-democracy demonstrators in North Africa and the Middle East, and for military intervention in Ivory Coast and Libya.

When Ban took over as U.N. chief from Kofi Annan, he called himself “a harmonizer and bridge-builder” and promised to push for peace in the Middle East and Sudan’s Darfur region. He said he also wanted to restore the U.N.’s reputation after scandals over the U.N. oil-for-food program to help Iraqi civilians and corrupt procurement officials.

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 that has deepened unemployment and poverty.

Ban told reporters he was proud of what the U.N. has accomplished on climate change, which he said will remain at the top of his agenda.

Of the Arab uprising, he said: “This is a once-in-a-lifetime generation opportunity to advance freedom and democracy. ... The United Nations will support these efforts to the maximum.”

The U.N. chief has won endorsements from two former U.S. ambassadors who served during George W. Bush’s presidency, John Bolton and Zalmay Khalilzad, for successfully navigating the U.N.’s bureaucracy and for showing he is committed to advancing human rights and democracy.

But Human Rights Watch has been very critical of Ban for failing to raise China’s rights record or the imprisonment of 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 insisted again Monday that he has spoken out for human rights, regardless of how powerful the country.

Philippe Bolopion, U.N. director for Human Rights Watch, told the AP that Ban has been much more vocal against human rights abuses in Egypt, in Libya, in Ivory Coast.

“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.