WASHINGTON (Reuters) - U.S. President Barack Obama on Friday said he was confident that United Nations secretary general-elect Antonio Guterres would be an effective leader of the international organization.

“He has an extraordinary reputation,” Obama told reporters ahead of his meeting at the White House with Guterres, a former prime minister of Portugal.

Noting that Guterres had led multilateral delegations at the highest levels, Obama said he had “great confidence” that Guterres would be able to ensure that the U.N. would be able to operate efficiently and effectively when taking on issues such as climate change and the international refugee crisis.

“At a time when those challenges are mounting, having an effective partner in the United Nations secretary general will be critically important,” Obama said.

Guterres will take over as head of the world body for five years on Jan. 1, 2017. He was Portugal’s prime minister from 1995 to 2002 and U.N. High Commissioner for Refugees from 2005 to 2015.

Obama and Guterres were expected to discuss cooperation between the United States and the United Nations.

Guterres said he was ready to forge a relationship with U.S. President-elect Donald Trump’s administration.

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He said he was totally committed “to work closely with the United States in the present administration” and “also with the next administration.”

Trump, who takes office Jan. 20, has named South Carolina Governor Nikki Haley, who has relatively little foreign policy experience, as the next U.S. ambassador to the United Nations.

The real estate magnate’s unconventional campaign prompted uncertainty about how his administration will handle international relations. Some of his campaign promises, such as building a wall along the U.S.-Mexican border and suggesting NATO partners need to pay more for their security, have raised concerns among allies.

Trump was slated to meet with John Bolton, who served as U.S. ambassador to the U.N. under President George W. Bush, on Friday. Bolton, who is in the running for a cabinet position, has called for major reforms to the U.N.