The major coalitions that participated are the Koalisyon ng Katapatan at Karanasan sa Kinabukasan, composed of parties that support the candidacy of President Gloria Macapagal Arroyo, and the Koalisyon ng Nagkakaisang Pilipino, composed of parties that support the candidacy of film actor Fernando Poe Jr. coalition.

The Alyansa ng Pag-asa was a minor coalition made up of Aksyon Demokratiko and Partido para sa Demokratikong Reporma–Lapiang Manggagawa.

Philippine Senate elections are via pluraity block voting, with the entire country as an at-large "district".

Arroyo was seeking a full term under the K4 coalition with Senator Noli de Castro, an independent, popular politician, as her running mate.

The three major parties supporting this coalition were Roco's Aksyon Demokratiko, former National Defense Secretary Renato de Villa's Partido para sa Demokratikong Reporma, and former Cebu Governor Lito Osmeña's Probinsya Muna Development Initiative.

This coalition led by Makati Representative Butz Aquino was composed of Panfilo Lacson's supporters from LDP party.

K4's Pia Cayetano, Dick Gordon, Lito Lapid, Bong Revilla, Mar Roxas and KNP's Jinggoy Estrada, Alfredo Lim and Jamby Madrigal are the neophyte senators.

The winners in the Senatorial and Party-list Representative elections were declared on May 24, with the exception of the 12th senator which was announced on June 3.