MANILA -- President Rodrigo Duterte's son on Tuesday joined a crowded race to become the speaker of the Philippines' parliament, in a move that could cement his family's grip on power.

"I am now going to join the race for speaker," Congressman Paolo Duterte said in a statement on Tuesday. "The House is divided, I might be able to help unite it. We were all voted for by the people."

The younger Duterte previously opted not to join the race to become speaker, but flip-flopped amid a heated internal dispute among allies seeking the speakership. A successful bid would raise concerns about Duterte further solidifying his political dynasty, with all his three children now holding political posts.

The president said earlier he would resign should Paolo run, but his spokesman on Tuesday walked back his pronouncement.

"It's between the father and the son. As a general principle, if you are qualified to run, you can run," presidential spokesman Salvador Panelo said.

Paolo, 44, would compete against former Foreign Affairs Secretary Alan Peter Cayetano and other allies, Lord Allan Velasco and Martin Romualdez. The younger Duterte has also floated the idea of equally sharing the House leadership over the next three years.

Paolo is Duterte's second child. Before entering Congress, he served as Davao's vice mayor from 2013. He abruptly resigned from that position amid allegations that he was involved in helping smuggle an estimated $118 million worth of methamphetamine from China. He has denied involvement and he has not been charged.

Duterte's eldest daughter, Sara, was in May reelected mayor of Davao City. Last year, she played a key role in unseating then speaker Pantaleon Alvarez and installing former President Gloria Arroyo as congressional leader. Sara also led a loose coalition of senatorial candidates in May, with most of them winning Senate seats.

Sebastian, the youngest, has been elected vice-mayor of Davao City.

The squabbling for the speaker position among Duterte's allies comes at a time when he needs to fortify his hold in Congress. Having just entered the second half of his six-year term, the president remains widely popular, but traditionally support for presidents wanes once politicians start preparing for the next presidential election.

Duterte held a "super majority" in the House of Representatives in the previous Congress, allowing him to win approval for controversial measures such as reforming the country's tax laws, granting free college education, and imposing martial law in the Philippines' southern islands.

However, the leadership change last year led to a budget impasse that dragged economic growth to a four-year low in the first quarter.

Ramon Casiple, executive director of the Manila-based Institute for Political and Electoral Reforms, said the younger Duterte's bid to lead Congress is a long shot.

"He doesn't have the background for it. He's a neophyte," Casiple said.

Casiple said, however, the situation remains fluid and backroom negotiations are expected to continue until the new congress convenes on July 22.

"You cannot be sure until the voting day," he said.