Cory's 1986 Presidential Campaign

Aquino participated in many of the mass actions that were staged in the two years following the assassination of her husband. In the last week of November 1985, Marcos unexpectedly announced a snap presidential election to be held in February 1986. Initially, Senator Salvador Laurel of Batangas, the son of a former president, was seen as the favorite presidential candidate of the opposition, under the United Nationalists Democratic Organizations. However, business tycoon Don Joaquin "Chino" Roces was not convinced that Laurel could defeat Marcos in the polls. Roces initiated the Cory Aquino for President Movement to gather one million signatures in one week for Aquino to run as president.

Aquino was reluctant at first to run for presidency, despite pleas that she was the one candidate who could unite the opposition against Marcos. She eventually was convinced following a ten-hour meditation session at a Catholic convent. Laurel did not immediately accede to calls for him to give way to Aquino, and offered her the vice-presidential slot under his UNIDO party. Aquino instead offered to give up her affiliation with her husband's political party, the Lakas ng Bayan (LABAN), which had just merged with Partido Demokratiko Pilipino, and run under the UNIDO banner with Laurel sliding down to the vice-presidential slot. Laurel gave way to Aquino to run as President and ran as her running-mate under UNIDO as the main political umbrella of the opposition.

In the succeeding political campaign, Marcos charged that Aquino was being supported by communists and agreed to share power with them, to which she responded that she would not appoint one to her cabinet. Marcos also accused Aquino of playing "political football" with the United States with respect to the continued United States military presence in the Philippines at Clark Air Base and Subic Naval Base. Marcos also derided Aquino as "just a woman" whose place was in the bedroom.

The elections held on February 7, 1986 were marred by the intimidation and mass disenfranchisement of voters. Election day itself and the days immediately after were marred by violence, including the murder of one of Aquino's top allies, Antique governor Evelio Javier. While the official tally of the Commission on Elections (COMELEC) consistently showed Marcos in the lead, the unofficial tally of the National Movement for Free Elections indicated that Aquino was leading. Despite the job walkout of 30 COMELEC computer technicians alleging election-rigging in favor of Marcos, the Batasang Pambansa, controlled by Marcos allies, ratified the official count and proclaimed Marcos the winner on February 15, 1986. The country's Catholic bishops and the United States Senate condemned the election, and Aquino called for a general strike and a boycott of business enterprises controlled by Marcos allies. She also rejected a power-sharing agreement proposed by the American diplomat Philip Habib, who had been sent as an emissary by U.S. President Ronald Reagan to help defuse the tension.