In 1971, Petkoff left the PCV to found, along with other dissidents, the Movement Towards Socialism (MAS). He was a member of Congress and twice an unsuccessful candidate for president, gaining 4% in the 1983 presidential election and 3% in the 1988 presidential election.

In 1998, Petkoff left the MAS because he was against its support of Hugo Chávez’s candidacy (see [1]) in the 1998 Presidential election. He left the political world and became a journalist, working as a director of El Mundo. Afterward, he founded his own newspaper, Tal Cual. Tal Cual has been outspoken in its criticism of both Chavismo and those who supported the 2002 coup attempt against Chávez.

Petkoff wrote several political books. In 2005 he published The Two Lefts (Las dos izquierdas, Alfadil Editor, Hogueras Collection) where he analyzed the resurgence of left-wing politics in Latin America. Petkoff argued that there was a sharp difference between the governments of Luiz Inácio Lula da Silva, Néstor Kirchner, and Ricardo Lagos, compared to the governments of Chávez and Castro, which he characterises as similar. The main ideas can be read in an article published in the journal New Society (Nueva Sociedad) in Spanish (see Las dos izquierdas).

On 21 April 2006, after rumours indicating that a number of intellectuals and middle-class liberal activists had asked him to run in the 2006 Presidential election, Teodoro Petkoff launched his campaign to be the next president of Venezuela. In a short televised message he explained his reasons and asked Venezuelans to follow his lead in the construction of what he described as a new, better Venezuela. On 4 August 2006, Petkoff dropped out of the presidential race. Five days after dropping out of the race, he endorsed Manuel Rosales, former governor of Zulia State, for the presidency.

In July 2008 the Inter-American Dialogue published a paper by Petkoff about Venezuela under Chávez, saying “Chávez’s Venezuela is a Bonapartist democracy of sorts, a one-of-a-kind ‘dictatorship.’ He aims to make the armed forces the institutional base of his power.”

On 12 May 2012, Petkoff and his wife were mugged by an armed man on a motorcycle after leaving a Caracas restaurant. In December 2012, while on the island of Margarita, Petkoff suffered a fall and sustained injuries that required surgery. Petkoff died on 31 October 2018.