Grace Poe has been a senator for just over two years.

AFP/Manila

The adopted daughter of a Philippine film star will on Wednesday announce a run for the presidency, and analysts say she could ride her father's popularity to a stunning win despite little political experience.

Grace Poe, 46, has been a senator for just over two years and faces legal challenges over her nationality. But her status as the daughter of the late Fernando Poe makes her a serious wild card chance, they said.

Her spokeswoman released a statement on Tuesday stating Poe would the next day "make an important announcement in connection with her plans for the (May) 2016 national elections".

Poe's aides refused to say if it would be the long-awaited confirmation of a presidential run, but the national media and political analysts said she definitely would.

"Grace Poe is clearly serious in gunning for the presidency. She has formed a campaign team comprised of her father's former supporters," Louie Checa Montemar, political science professor for Manila's De La Salle University, told AFP.

According to her official narrative, Poe was abandoned inside a church in a small central Philippine town just after being born. She still does not know who her biological parents are.

The country's most popular movie star couple, Poe and Susan Roces, then adopted her.

In the Philippines' colourful brand of democracy, many movie stars and other celebrities use their popularity to launch successful political careers.

Poe's father, with no previous political experience, narrowly lost the 2004 elections amid allegations his opponent Gloria Arroyo stole crucial votes from him. He died seven months after the election.

But Grace Poe then showed the family name still had massive political capital by securing the most votes in the 2013 senatorial elections.

At that time she had no political experience and had only recently returned from the US, where she had become a naturalised citizen.

Only Filipino citizens can run for the presidency.