"I started boxing because I wanted to help my mother," Pacquiao told reporters in Beverly Hills at a news conference to promote his third fight against welterweight champion
Pacquiao said the April fight will be his last. "I end it because I want to help my countrymen. … Boxing has been my passion. Public service is my calling. … If [presidency] is my destiny, no one will refuse that."
Pacquiao, 37, is a congressman seeking election on May 9 to become one of 12 senators in the Philippines. Victory would give him a six-year term, and leave one the country's best-known citizens strongly positioned to run for the presidency in 2022.
"He can do so much for the Philippines nation. He doesn't take. He gives. And that's not usually what politicians do," Pacquiao promoter Bob Arum said.
Pacquiao will fight for the first time since May 2, when he lost a unanimous decision to
Pacquiao earned more than $150 million, but he was criticized about his decision to proceed with the fight after suffering a right shoulder injury in camp that he aggravated in the fourth round.
"I never regret I pushed that fight," Pacquiao said. "In fact, I thought I won the fight."
Mayweather (49-0) announced his retirement following a September victory over Andre Berto and turns 39 next month. But his father/trainer, Floyd Mayweather Sr., said that Floyd Jr. could still opt to return to the ring.
Arum on Tuesday said he could envision a scenario where Pacquiao fights impressively in April, and Mayweather expresses interest in a rematch.
"That's another story, a question I cannot answer, because we don't know what's tomorrow," Pacquiao said. "I'm OK. [Mayweather] retired already, so I'm going to retire also. … My family wants me to retire."
Pacquiao is scheduled to have his shoulder examined again before he departs for a Thursday news conference in New York, but declared, "my shoulder is healed 100%. I can confidently throw my right hand and jabs because it's already fixed."
Pacquiao (57-6-2, 38 knockouts) expressed contentment in closing his career by ending his trilogy with Bradley (33-1-1, 13 KOs).
Tickets for the bout, priced from $154 to $1,204, go on sale Friday at 10 a.m. through Ticketmaster.
"I'm so grateful … I can prove I can still fight to the end," Pacquiao said.
Bradley defended his World Boxing Organization belt impressively on Nov. 7 with a ninth-round technical knockout of Brandon Rios.
Pacquiao said he noticed improved "power and techniques" from Bradley under new trainer Teddy Atlas, and said he expects "a better fight" than their first two bouts, praising Bradley's body punching.
In 2012 Bradley won a controversial split-decision victory over Pacquiao, and Pacquiao responded by convincingly winning the 2014 rematch with a unanimous decision.
"I want a clear victory. I will do my best to prove that Manny Pacquiao is still in his prime, still at the top, before I hang up my gloves," Pacquiao said.
"This is not about the money. It's about legacy, about how I end my career. I've announced this is my last fight. … If you want to see me after this fight, you'll have to come to the Philippines, and I recommend the Philippines for everyone's vacation."