MANILA - Former Sen. Antonio Trillanes IV said Monday he would seek the country's highest office if Vice President Leni Robredo would not run in the 2022 elections.

Trillanes said he already met with members of newly launched coalition 1Sambayan during an interview in January.

"I qualified at the start of the interview. I said that the opposition is solidly behind and united behind the candidacy of Vice President Leni Robredo for President. So, any scenario of the Vice President withdrawing her candidacy is the only condition that I’d entertain entering the presidential derby," he told ANC.

The senator, however, maintained that Robredo had a greater chance of winning next year's elections.

"In terms of qualification, definitely she's highly qualified and we believed she's the most winnable candidate in the opposition," he said.

"That's why we are pushing her [and] we are assuring her we would be with her in this fight for the presidency in 2022."

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The 1Sambayan, which is led by the country's former high-ranking officials, is looking to endorse a candidate who has a clean track record, an upright stand on key issues and platforms that address current problems.

The coalition had already met some possible candidates, including Robredo, Trillanes, Manila Mayor Isko Moreno, senators Grace Poe and Nancy Binay.

In the interview, Trillanes dismissed surveys that President Rodrigo Duterte was still enjoying high approval rating from the public.

"We are conducting our own internal polling. His numbers are significantly down and continues to decline at a very steep rate," he said.

Asked about the possible tandem of Duterte and his daughter Sara in next year's elections, Trillanes has this to say.

"I encourage them to do that. They have every right to do that. In fact, ideally, I would want them to be rejected in 2022 elections," he said.

"So, it's even preferable for Mr. Duterte to run for Vice President or Sara Duterte to run for President. We're looking forward to that rejection, to their rejection in 2022."