Metro Manila (CNN Philippines) — Presidential candidate Davao City Mayor Rodrigo Duterte and vice-presidential bet Sen. Ferdinand "Bongbong" Marcos Jr. maintained their leads in the latest Pulse Asia pre-electoral national survey conducted from April 16 to 20.

The top headline during the survey period was Duterte's rape slur that received flak from women's groups, international ambassadors, and international media. It was also when he flip-flopped from his apology for the remark.

Related: Duterte lashes out at foreign envoys, women's group

Despite the issue hounding Duterte, he still emerged to the top of the presidential race with 35 percent, enjoying a 12-percentage point lead over Sen. Grace Poe (23 percent).

Liberal Party (LP) bet Manuel "Mar" Roxas II (17 percent) is statistically tied with Vice President Jejomar "Jojo" (16 percent) in third place. Sen. Miriam Defensor Santiago still remained in the last spot with 2 percent. Six percent still remained undecided.

The survey has a ± 2.3 percent error margin.

1,800 registered voters were asked in face-to-face interviews: "If the coming May 2016 elections were held today, whom would you vote for as PRESIDENT OF THE PHILIPPINES?"

Marcos still leading VP

Marcos continued to lead the vice-presidential race with 29 percent.

In second place is Camarines Sur Rep. Leni Robredo (24 percent). Sen. Francis "Chiz" Escudero (18 percent) and Sen. Gringo Honasan (16 percent) are in third and fourth place, respectively. In the last spot is Sen. Antonio Trillanes IV (3 percent). Seven percent still remained undecided.

The vice-presidential debate hosted by a TV network happened on April 17. Marcos and Honasan were unable to attend the said debate.

Top senatorial candidates

The latest Pulse Asia survey said the leading candidates for the senatorial race are Sen. Vicente "Tito" Sotto III and Senate President Franklin Drilon.

The other candidates on the list are former senators Francis "Kiko" Pangilinan, Panfilo "Ping" Lacson, and Juan Miguel Zubiri.

The survey result also listed other probable winners in the May 2016 senatorial elections: Sarangani Rep. Emmanuel "Manny" Pacquiao, Sergio R. Osmeña III, former Akbayan Party List Rep. Risa Hontiveros, Sen. Ralph Recto, former Sen. Richard Gordon, Valenzuela City Rep. Sherwin T. Gatchalian, former Technical Education and Skills Development Administration (TESDA) Director General Emmanuel Villanueva, and former Justice Secretary Leila de Lima.

The survey result was released on Tuesday (April 26).