RIO DE JANEIRO (Reuters) - Brazil’s Foreign Minister Jose Serra labeled the possibility of a Donald Trump presidency a “nightmare” and urged all Americans to vote for Democratic contender Hillary Clinton.

Brazilian Foreign Minister Jose Serra speaks next to Mexico's Foreign Minister Claudia Ruiz Massieu (not pictured) during a news conference at the foreign ministry building (SRE) in Mexico City, Mexico July 25, 2016. REUTERS/Henry Romero

In an interview published Sunday in the Brasilia-based Correio Braziliense newspaper, Serra was asked “in the case of the USA, Trump or Hillary?”

“I consider the hypothesis of Trump a nightmare,” said Serra, a U.S.-educated economist. “Do nightmares, at times, come true? They do, but I prefer not to think about this.”

Trump, the Republican nominee for the White House, has often irked those outside the United States with his views and foreign diplomats have told U.S. government officials they are worried about the xenophobic nature of Trump’s rhetoric, according to administration sources.

Serra, a two-time losing presidential contender and former health minister who developed Brazil’s lauded anti-AIDS program in the 1990s, is serving as foreign minister under interim President Michel Temer.

He could be Brazil’s top diplomat for at least a few years under Temer, who took the spot of suspended President Dilma Rousseff. She is facing an impeachment trial for alleged budget irregularities and is widely expected to be permanently ousted by Brazil’s Senate in late August or early September.

When Serra took over as foreign minister of Latin America’s biggest economy in mid-May, he quickly reversed some foreign policy stances, emphasized that Brazil needs to seek bilateral trade deals, and shifted the nation away from its close ties to Venezuela and other more left-wing nations in Latin America.

But when it comes to the United States, Serra said that he “always cheered for the Democrats, wholeheartedly.”

Serra holds a masters and a doctorate in economics from Cornell University, where he studied after being exiled from Brazil after the 1964 military coup.

He said the choice between Clinton and Trump is not a matter of being a Democrat or Republican, “but of being wise.”

“Anybody who wants the best for the world should support Hillary, in my view,” he said.

Brazil’s Foreign Ministry did not immediately respond to requests for comment.