Oviedo was nominated as the Colorado candidate for president in the 1998 election. However, when the Supreme Court upheld in April his conviction on charges related to the 1996 coup attempt, he was not allowed to run and was detained in jail. His former running mate, Raúl Cubas, became the Colorado Party's candidate, and was elected in May in elections deemed by international observers to be free and fair. One of Cubas' first acts after taking office in August was to commute Oviedo's sentence and release him. In December 1998, Paraguay's Supreme Court declared these actions unconstitutional. In this tense atmosphere, the murder of Vice President and long-time Oviedo rival Luis María Argaña on 23 March 1999, led the Chamber of Deputies to impeach Cubas the next day. On 26 March, eight student anti-government demonstrators were murdered, widely believed to have been carried out by Oviedo supporters. This increased opposition to Cubas, who resigned on 28 March. Senate President Luis González Macchi, a Cubas opponent, was peacefully sworn in as president the same day.