Philippine Senator and presidential candidate Grace Poe speaks next to her running mate vice-presidential candidate Chiz Escudero during a news conference in Antique province in central Philippines, Jan. 12, 2016. Reuters/Erik De Castro

The race for the Philippine presidency and vice presidency tightened in the latest survey released by one of the country's two big polling groups.

For the presidency, Senator Grace Poe's popularity slipped to 26 percent in a Feb. 15 to 20 survey by Pulse Asia, compared with 30 percent in its January poll. Vice President Jejomar Binay inched up to a near-tie of 25 percent, from 23 percent in January. The survey covered 1,800 registered voters with a 2 percentage point margin of error.

For the vice presidency, which is voted on separately, Senator Chiz Escudero slipped to 29 percent from 33 percent while Senator Ferdinand Marcos Jr., known as "Bongbong," rose to 26 percent from 23 percent.

The survey was conducted amid continuing Supreme Court hearings on petitions to disqualify Poe on residency or citizenship grounds. As a foundling, her parents and their nationality are unknown, raising questions about whether she is a "natural-born" citizen, as the constitution requires. The residency issue stems from a dispute on when she returned from the U.S., where she lived for most of her 20s and 30s. The constitution requires 10 years of Philippine residency. The court is expected to vote on the issues next week, according to The Philippine Star.

It was also before the 30th anniversary of the ouster of Ferdinand Marcos, the current senator's father, on Feb. 25, 1986. The anniversary triggered many stories in traditional and social media about the elder Marcos' two-decade regime, including alleged corruption and human rights abuses. President Benigno Aquino — whose mother Corazon succeeded the elder Marcos — urged voters to spurn the son.

Aquino is barred from seeking a second term in the May 9 elections. The survey showed his candidate for president, Manuel Roxas, was tied for third place with Davao City Mayor Rodrigo Duterte at 21 percent. Aquino's bet for vice president, Leni Robredo, was in third place at 19 percent.

Binay leads Poe in the early February survey by Social Weather Stations, the country's other big polling group.