A tough-talking Philippine mayor has widened his lead in a poll ahead of May 9 presidential elections, but analysts say his chances will likely be hurt by a storm of criticism over a rape joke and offensive remarks against foreign allies.

Mayor Rodrigo Duterte of southern Davao city led with 34 percent of 4,000 respondents in the Pulse Asia survey released Sunday. Sen. Grace Poe followed with 22 percent in the survey commissioned by the ABS-CBN TV network.

Pulse Asia President Ronald Holmes says the survey was concluded before Duterte's remarks in which he joked he wanted to be the first to rape an Australian missionary who was killed by prisoners in a riot. He also told the U.S. and Australian ambassadors to shut up over the issue.