Arum said he had discussed plans for a final fight with Pacquiao last week in New York — where Pacquiao received the Asia Game Changer award presented by the Asia Society at the United Nations.
“I’m telling you what he told me last week at dinner in New York,” Arum told the website. “We talked very seriously and he said, ‘Bob, hopefully, by the middle of May I will have been elected senator in the Philippines and at that point I cannot engage in boxing because I need to focus on the senate and I have to be in attendance.’
“Manny told me this fight on April 9 will be his last fight.”
That echoed comments Pacquiao himself made in the Philippines this month, when he announced he would run for a senate seat.
An opponent has not been named, although Arum mentioned England’s Amir Khan, a former unified junior welterweight titleholder, as well as unbeaten junior welterweight champion Terence Crawford.
Arum named Juan Manuel Marquez and Timothy Bradley as other potential foes.
Mexico’s Marquez (56-7-1, 40 KOs), has said he is not interested in extending his great rivalry with Pacquiao to a fifth fight while Bradley would have to get past Brandon Rios in November to be considered for a third fight against PacMan.
Bradley was awarded a controversial split decision in their 2012 fight that most thought Pacquiao had won, and Pacquiao won a 2014 rematch.
The venue for the bout also remains uncertain, although Arum said he expected it to be in Las Vegas.
Pacquiao, who has won eight world titles in as many weight divisions, owns a ring record of 57-6-2 with 38 knockouts.