Vice mayor of Dasmariñas (2016–2025)
Mangubat ran and won as Barzaga Jr.'s running mate for vice mayor of Dasmariñas in the 2016 elections under the NUP ticket. When Barzaga Jr. ran for the House of Representatives in 2019, Mangubat was selected as his wife Jenny's running mate for vice mayor. He ran under the PDP–Laban banner and won. Mangubat sought a third term as vice mayor in 2022, rejoining the NUP, and won against Valeriano Encabo and Teodorico Remulla, who both ran as independents. As vice mayor, he presided over the city council.
Mangubat's third consecutive term ended in 2025, and he was succeeded by Jenny Barzaga's son, Elpidio "Third" Barzaga III.
Congressional bid (2026)
Jenny Barzaga's son, Kiko, ran for the city's congressional seat in the House of Representatives in 2025 and won. He was first suspended by the House for 60 days in December 2025 for repeated reckless social media behavior, before being suspended again in February 2026. He was expelled on June 2, 2026, by a vote of 265–14–8, becoming the second lawmaker in Philippine history to be expelled from the House.
In June 2026, supporters began urging Mangubat to run for the vacant seat on social media and in community chat groups. He said he was studying his next steps. Former congressman Gilbert Remulla was also reported as a possible contender.
Mangubat was the first to file his certificate of candidacy (COC) for the special election held on August 29, 2026 to fill the vacant seat, filing it on July 15, the first day of filing, at the Dasmariñas New City Hall. He ran as an independent against incumbent Dasmariñas mayor Jenny Barzaga, former city councilor Jesse Frani, and two other independent candidates, Marvin Dupal-ag and Leysander Ordenes.
Mangubat faced criticism for running against the family of Barzaga Jr., with whom he had served. In response, he said he remained grateful to Barzaga Jr. for opening the door to public service for him, but that public service was not a lifelong political debt, and that his candidacy was not a rejection of Barzaga Jr.'s legacy.
Mangubat ran on a platform of support for the anti-political dynasty bill, local healthcare reform, and improvements to city-wide water supply services. He named healthcare as his first priority, citing the many families relocated to the city from Metro Manila who could not afford hospital care or medicine, followed by shortages and inconsistency in the city's water supply. His campaign slogan was "Challenge accepted para sa Dasmariñas".
Mangubat conceded on the night of the election, based on partial and unofficial results, and congratulated Barzaga. He was defeated by Barzaga by a wide margin, receiving 30,373 of the 258,371 votes cast; Frani placed third with 24,350 votes. Turnout was 57.75 percent of the district's 447,387 registered voters.
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