"So at least verbally he said he was coming", said Paynor, who also heads the National Organizing Committee of this year's ASEAN Summit.
"As of now, President Trump, for instance, when President Duterte called him up to congratulate him had already indicated that he was coming in November", Paynor said. The day's meetings will be culminated by a gala dinner hosted by President Rodrigo Duterte, chair of the 30th ASEAN Summit.
The outcome of the informal summit between United States President Donald Trump and Chinese President Xi Jinping was good for Asean - as it exceeded Asean leaders' expectations. "And numerous leaders who do not attend do so because they have internal issues, which prevents them from coming", Mr. Paynor also said.
But Duterte is not sure whether his United States counterpart would visit the Philippines.
2017 is a full year for ASEAN and its current annual host, founding member-nation the Philippines.
ASEAN, which is marking its golden anniversary this August, groups Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam.
"We usually expect 100 percent attendance", Paynor told reporters, when sought for confirmation on Trump's attendance on Asean summit later this year.
Leaders from New Zealand, South Korea, the US, Japan, Australia, China are expected at the meeting, along with representatives from ASEAN's 9 other member states. "And numerous leaders who do not attend do so because they have internal issues which prevent them from coming", Paynor said.
Duterte's bilateral talks with Widodo and Bolkiah coincide with the 30th Asean summit that will be held in Manila, starting April 26 to 29.
Meanwhile, the President is also expected to hold separate bilateral meetings with Indonesian President Joko Widodo and Sultan Haji Hassana Bolkiah of Brunei next week.
He said President Duterte may have "pull-aside" meetings with the other leaders.
According to Paynor, Widodo's visit will be in reciprocation to the state visit of Duterte to Indonesia last September.