As the two-party system in the military dictatorship ended and the redemocratization process began, Oliveira officially affiliated himself with the newly renamed PMDB, being elected as a federal deputy in 1982.

[4][5] Although the idea for creating a constitutional amendment to reestablish direct presidential elections cannot be credited to Oliveira entirely, his proposed amendment and its subsequent failure in the National Congress had massive repercussions, as the movement for direct democracy in Brazil grew beyond the Congress, and became a popular movement in Brazil known as Diretas Já.

[6] Fearful of what was occurring in Congress, then leader of the military dictatorship João Figueiredo strongly pressured members of the dictatorship-aligned PDS to vote down the measure.

[7] Despite this, the central faction of the movement began to take to the streets, with an IBOPE poll taken on the eve of the eventual vote showing that 84% of those questioned approved of the amendment.

His political reputation was damaged when it was alleged that João Arcanjo Ribeiro, who was involved with organized crime in Cuiabá, helped fund his reelection campaign in 1998.

[4] In 1995, then-president Fernando Henrique Cardoso awarded Oliveira the Grand Officer class of the Order of Military Merit by decree.

[10] While tentatively planning to run once more as a federal deputy, Oliveira died on 6 July 2006 in Cuiabá due to pneumonia that was exacerbated by complications from diabetes.