In Isabela, Basilan, although a part of this region, the voters elect their representative via Basilan's legislative district. Isabela is politically within Basilan despite being in a separate regions.
The UNA-ZTZ coalition fielded former Monsignor Crisanto dela Cruz for the post. Dela Cruz previously run for the mayorship in 2007 and for the vice-mayorship in 2010. This was the second time where Dela Cruz and Mayor Lobregat went against each other; the previous time was in the 2007 mayoral elections.
2013 Philippine House of Representatives election at Zamboanga City's 1st district
Incumbent Erico Basilio Fabian was term limited and ran for the mayorship instead. He then formed a local coalition known as Fuerza Zamboanga, yielding District II Councilor Lilia Nuño to replace him.
The AZAP coalition nominated Mayor Lobregat's brother, Jose Lobregat.
The ZTZ coalition recruited former City Vice-Mayor Mannix Dalipe.
2013 Philippine House of Representatives election at Zamboanga City's 2nd district