“I believe [Go’s] withdrawal signifies that concessions have already been made with the Bongbong Marcos camp, primarily the protection from prosecution, which includes the ICC,” former senator Antonio Trillanes IV said on Tuesday.

However, Commission on Elections spokesman James Jimenez pointed out that Go was still technically in the running as he had not given official notice to the poll body that he was pulling out, Tuesday being a public holiday.

Go’s announcement did not surprise politicians because at a Duterte-backed event just last week endorsing him as the official presidential candidate from the ruling PDP-Laban party, the 47-year-old senator appeared to be having cold feet.

At the November 24 gathering attended by some 50 of the 81 provincial governors, Go said that “it’s not yet my time”, shared his misgivings about running, and reportedly wept.

That same day, Go also told reporters he was waiting for God to give him an encouraging sign to run.

He confessed to being stunned by the turn of events and had not completely processed them. “I was taken aback. It still has not sunk in yet why I am a candidate for president,” he told reporters.

Ramon Casiple, co-founder of Manila political think tank Novo Trends, said he thought Go’s sudden exit meant Duterte and his daughter, Davao City Mayor Sara Duterte-Carpio, had patched up their quarrel over her unilateral decision to run for the vice-presidency under Marcos Jnr, even though she was topping opinion polls.

“That was the reason why Duterte wanted a presidential bid for Go in the first place, because the problem was, the father was left out of the negotiations,” Casiple said.

Former congressman Neri Colmenares, who is running for senator under the left-wing Bayan Muna [Country First] Party, described Go as Duterte’s “bargaining chip” who was used as “leverage to get as many concessions as possible” with Marcos Jnr.

“Even if Duterte does not admit it, he is afraid of the International Criminal Court and the reality that he could become the first Asian [leader] to be convicted and jailed for crimes against humanity,” Colmenares said in a statement.

Jean Franco, a political-science professor at the University of the Philippines, said she was inclined to believe that Go’s presidential run was “mere strategy … but it is certain that Go’s withdrawal had the blessing of Duterte, given the former’s loyalty”.

Trillanes, who is running for senator, noted that it was an “awkward situation” for Go to be running for president when the daughter of his boss was teaming up with another candidate.

“Based on our info, at first Duterte was genuinely pissed off that Sara wasn’t running for president, so he pushed Bong Go to run instead,” said Trillanes. But when Duterte realised Go was likely to lose, the plan was off, he added.

During the November 24 event, Duterte was said to have told those in attendance that if Go dropped his presidential bid, “I will just stay neutral. I’ll just keep quiet”, Rappler reported, quoting Cagayan governor Manuel Mamba who was at the event.

“‘I did not agree with Sara’s decision but she is my daughter. I am obliged to love her’,” Mamba quoted Duterte as saying.

Over the last two weeks, Duterte has been titillating the public with claims about a cocaine-snorting presidential candidate – whom he said he would name in due time. The person was widely perceived to be Marcos Jnr, even by his own supporters.

Duterte has also openly criticised Marcos Jnr by name as “spoiled” and a “weak” leader.

Trillanes said in return for protecting Duterte from criminal prosecution, Marcos Jnr “would probably want him to keep quiet” during his presidential campaign.

“At some point, however, they would have very good words for each other’s candidacies,” he said. Duterte is running for senator.

Amid the dramatic twists and turns of Philippine presidential elections, Casiple said “wily” Duterte had lots up his sleeve. “If [a move] is at all possible, he’ll think of it.”

For instance, Duterte could capitalise on cases to disqualify Marcos Jnr from contesting as president, Casiple said.

Philippine election laws are such that if Marcos Jnr is officially proclaimed the winner, Duterte could still prod the Commission on Elections (Comelec) to disqualify him based on the pending cases against him. This includes a 1995 conviction for tax evasion which carries the accessory penalty of a lifetime ban on taking public office. While Comelec is constitutionally an independent body, it so happens that by election day, it will consist entirely of Duterte appointees.

“If Marcos is disqualified after he is proclaimed the winner, then Sara – if she wins as vice-president – will become the president and that’s all allowed in the Philippine Constitution,” said Casiple, who is also a board trustee of the Institute for Political and Electoral Reforms.