Iggy Arroyo Lakas–Kampi Alejandro Mirasol Liberal A special election (known elsewhere as "by-elections") for Negros Occidental's 5th district seat in the House of Representatives of the Philippines was on June 2, 2012.

Binalbagan Mayor Alejandro Mirasol defeated Negros Occidental Provincial Board Member Emilio Yulo III in the election.

[5] On February 29, Belmonte, together with Negros Occidental representatives Alfredo Marañon III, Albee Benitez, Mercedes Alvarez and Julio Ledesma IV, filed a House resolution calling for a special election.

Possible candidates that were running include Arroyo's sister Marilou Arroyo-Lesaca (former representative of Ang Kasangga party-list), Binalbagan Mayor Alejandro Mirasol and Board Member Emilio Yulo III.

[10] The UNA meeting on March 24 ended in a stalemate as Mirasol and Yulo, his nephew, disagreed on how the nomination process will be conducted; Yulo wanted a ballot where the choice would be ticked, while Mirasol wanted a ballot where one has to write the name of the preferred nominee.

Other prospective candidates include former board member Enrique Montilla, a nephew of Arroyo-Lesaca, and former Isabela mayor Renato Malabor.

[13] On a resolution dated March 28, the commission set the election on June 2, with a budget of more than 21 million pesos.

Only Himamaylan Mayor Agustin Ernesto Bascon, who was not present at the caucus, did not support Mirasol, instead endorsing Yulo.

He admitted that while he won't match the financial resources of UNA and he only has the support of his cousin Mayor Bascon, he is not intimidated.

[16] On April 20, Macalintal and fellow lawyer Antonio Carlos Bautista questioned the legality of the special election "because it will be held beyond the period as provided for by law."

[17] Mirasol defected to the Liberal Party of President Aquino on May 5, along with his vice mayor and councilors, although he remained as a UNA member.