PHILIPPINE President Rodrigo R. Duterte’s preferred successor on Tuesday quit the presidential race, in another twist to an electoral contest that is dominated by influential clans.

Senator Christopher Lawrence T. Go, the president’s former aide, said he did not want to add to the problems of Mr. Duterte, whose daughter has teamed up with the only son and namesake of the late dictator Ferdinand E. Marcos.

“I do not want President Duterte to be caught in the middle,” Mr. Go told reporters in Filipino, based on a video posted by the state-run television’s Facebook page. “My love for him is more than that of a father.”

He also said he was not ready to run for president.

Candidates have been shifting parties and alliances in the runup to the 2022 elections, which appear to be still dominated by political dynasties and celebrities.

Mr. Go initially registered to run for vice-president. He changed his decision at the last minute after Davao City Mayor and presidential daughter Sara Duterte-Carpio decided to run for vice-president.

She is running under Lakas-CMD, the political party of ex-President Gloria Macapagal-Arroyo, a known powerbroker in Philippine politics. Lakas-CMD has adopted her running mate, Ferdinand “Bongbong” R. Marcos, Jr., as its presidential bet.

Earlier this month, Mr. Marcos’s Partido Federal ng Pilipinas and Ms. Caprio’s Lakas-CMD partnered with the political party founded by ex-President Joseph E. Estrada, who was toppled by a popular uprising in 2001. He spent years in prison before he was convicted for corruption and later pardoned by Ms. Arroyo.

The withdrawal of Mr. Go from the presidential race is just an attempt to “salvage the crumbling Duterte-Marcos alliance,” former Party-list Rep. and senatorial candidate Neri J. Colmenares said in a statement.

He said the President had “groomed” his former aide to be his shield from potential lawsuits after his six-year term ends next year. Mr. Duterte is barred by law from running for reelection.

Mr. Colmenares said it was clear from the start that Mr. Go had very little chance of winning and that the President was just using him as leverage to get as many concessions as possible from Mr. Marcos. “He is there to protect and benefit from the Duterte dynasty.”

Critics have said Mr. Duterte, who is running for senator, might be doing everything to protect himself from potential lawsuits.

The International Criminal Court’s (ICC) Office of the Prosecutor has said it would ask the Philippine government to provide proof that it is investigating its war on drugs that has killed thousands, after the tribunal suspended an initial probe.

The Philippines must submit concrete proof that it is taking steps to hold human rights violators accountable in Mr. Duterte’s anti-drug campaign, it said.

Also on Tuesday, a group representing drug war victims at the Hague-based tribunal asked ICC Prosecutor Karim Khan to continue its initial probe of the anti-drug campaign.

“Contrary to the claim of the Philippine government, there is no genuine domestic investigation, much less prosecution, being conducted into crimes against humanity in the context of the war on drugs campaign,” Rise Up for Life and Rights said in a letter to Mr. Khan.

The group cited an “unjustified delay and even aversion” on the part of the government in investigating and prosecuting crimes linked to the drug war.

The government’s Nov. 10 letter to the ICC’s Office of the Prosecutor explaining that it had been conducting investigations into the drug war is “incorrect and misleading.”

“The proceedings described in the letter do not involve investigations into crimes committed as part of a widespread or systematic attack against a civilian population pursuant to a state or organizational policy,” it said.

The group said the Department of Justice’s review of 52 cases out of the tens of thousands killed and probes supposedly carried out by police “deliberately treat the crimes individually and separately, ignoring any evident connection between the various acts.”

“The domestic investigations mischaracterize these crimes as isolated incidents involving a few errant police personnel, described by the Duterte administration as just a few bad apples,” Rise Up for Life said.

The government has taken an increasingly large role in targeting civilians, “no longer trying to create distance by outsourcing the majority of violence to vigilantes,” US-based Armed Conflict Location and Event Data Project said in a report on Nov. 18.

After analyzing data and information from at least 40 sources, the group said the Philippine government had been “undercounting” civilian deaths in the drug war.

At least 1,100 deaths in the drug campaign have not been counted by the government. “We now estimate at least 7,742 civilians have been killed in the drug war since 2016.” — Kyle Aristophere T. Atienza