MANILA, Philippines -- Philippine President Rodrigo Duterte said Friday he may not be able to survive his six-year term and seemed overwhelmed by the immensity of his work, including the drug menace he's trying to fight.

Duterte, 71, outlined in a rambling speech the obstacles he's confronting in his deadly crackdown on illegal drugs, the heavy workload of the presidency and his cloistered existence now, saying "it gets to be a very lonely life."

"Will I survive the six years? I'd make a prediction, maybe not," he said.

Duterte, who took office on June 30, did not explain exactly what he meant but said there were people who want him to be removed, citing his reaching out to China and his lashing out at the U.S., his country's treaty ally, after President Barack Obama and other American officials raised concerns over his anti-drug crackdown.

Duterte has been in the news in recent weeks for his expletives-laden outbursts against U.S., EU and UN officials, who have called for an end to the killings of drug suspects and raised human rights concerns. In one speech, he told Obama to "go to hell."

Duterte's trash talk has become a feature of his political persona. He suggested Friday that he was only joking when he recently announced that he had promised God he wouldn't swear again. He explained that he loses control when he feels he's being oppressed.

"When I'm threatened, I get scared but there is a certain point in my fear when, if I think that I may die or I'm at a disadvantage, that I'm being oppressed, I become wild," he said. "I really lose the civility in me."

Duterte, who has served as a prosecutor, a congressman and then as the longtime mayor of southern Davao city, said he is not obsessed with the presidency and could give it up to opponents without a fight.

"Those who don't want me, that's easy," Duterte said, adding that potential coup plotters did not have to waste their bullets and should just head to the presidential palace, and "we'll have coffee and I myself will swear you to run this republic and solve the problem."

"Do not give me a reason to go out because you might get your wish," Duterte said.