PRESIDENT Rodrigo R. Duterte on Monday night said he would campaign against boxing champion and Senator Emmanuel “Manny” D. Pacquiao if he fails to identify corrupt government officials.

“I’m challenging him, tell me which offices have corruption and I will take care of it,” he said in in a televised speech in mixed English and Filipino. “I will do something within a week.”

“If you will fail to do that, I will campaign against you, because you are not doing your duty,” he told Mr. Pacquiao.

The boxing legend, who had criticized the President’s stance on the country’s sea dispute with China, said state corruption is rampant. Graft is the main cause of poverty in the Philippines, he told the ABS-CBN News Channel.

Mr. Pacquiao, who serves as acting president of the ruling political party headed by Mr. Duterte, is believed to be seeking the presidency at next year’s elections.

The President said the senator should not think that he could solve graft once he becomes President.

“All these years you’ve said nothing but heaped praises for me,” Mr. Duterte said. “Now you say there’s corruption.”

The Philippines slipped two spots in a global corruption index released by Transparency International in January. Widespread corruption has weakened many countries’ response to the coronavirus pandemic, it said.

Efforts to control corruption in the Philippines has appeared mostly stagnant since 2012, the watchdog said.

“I accept President Duterte’s challenge,” Mr. Pacquiao said in a statement in Filipino on Tuesday. “Thank you for giving us the chance to help you by giving you information in the campaign against corruption.”

Mr. Pacquiao said the President himself had said in October that corruption in government was getting worse.

“In his own words, he said: ‘I will concentrate the last remaining years of my term fighting corruption because up to now, it’s not easing but rather increasing,’” the boxing champion said.

“For give me my beloved President, but I’m not a liar,” he said, adding that he is not corrupt.

He cited anomlies in the government’s purchase of rapid test kits, masks and other materials amid a coronavirus pandemic.

He asked the Health department to give a complete accounting of these expenditures. “Where did the money that we borrowed for the pandemic go? Sadly, we are arguing about issues of corruption. What the country needs are leaders who will help each other against it.”

“I think it’s rather obvious that the relationship between the President and Senator Pacquiao is not as cordial as it was,” presidential spokesman Herminio L. Roque, Jr. told a televised news briefing on Tuesday.

He said Mr. Duterte had not made up his mind whether to endorse Mr. Pacquiao for President next year.

“It seems Pacquiao is ready to break off with the President and is now dead set on running,” campaign strategist Gerardo Eusebio said in a Viber message. “Not hard to believe because we know he has the money.”

“From today until October, we will see a lot of realignments and shifting alliances,” he added.