On Sunday, leftist Gustavo Petro, a former member of the M-19 guerrilla movement who has pledged fundamental social and economic transformation, became the first progressive in Colombia's history to win the presidency.

Petro defeated construction magnate Rodolfo Hernandez by a margin of 716,890 votes, which was unexpectedly large. In pre-vote polling, the two candidates were technically deadlocked.

Senator Petro, a former mayor of the capital city of Bogota, has committed to combat inequality through free university education, pension reforms, and heavy taxes on unproductive land. He received 50.5% of the vote versus Hernandez's 47.3%.

Several investors have been alarmed by Petro's suggestions, particularly his restriction on new oil projects, although he has promised to honor existing contracts.

Alejandro Forero, 40, a supporter who used a wheelchair, cried as results trickled in at the Petro campaign celebration in Bogota.

"Lastly, praise God. I am confident that he will be a good president and will assist the less fortunate among us. This will soon change for the better "explained Forero, a jobless individual.

This was Petro's third presidential campaign, and his victory added the Andean nation to the list of Latin American countries that have recently chosen progressives.

Petro, 62, alleged that he was tortured by the military when he was jailed for his involvement with the rebels. His likely triumph has high-ranking military authorities preparing for a shift.

Francia Marquez, a single mother and former cleaner Petro's running mate will be the country's first Afro-Colombian female vice president.

"Today I'm voting for my daughter - she turned 15 two weeks ago and asked for just one gift: that I vote for Petro," said Pedro Vargas, 48, a security guard in the southwest of Bogota on Sunday morning.

"I hope this man fulfills the hopes of my daughter, she has a lot of faith in his promises," Vargas, who never votes, added.

In addition, Petro has committed to fully implementing a 2016 peace agreement with FARC insurgents and seeking dialogue with the still-active ELN guerrillas.

As a result of discrepancies in congressional tallies in March, he had cast questions on the integrity of the count. He had asked voters on Sunday to examine their ballots for extraneous marks that could render them worthless.

Hernandez, the former mayor of Bucaramanga, was an unexpected candidate in the runoff and has pledged to reduce the size of government and fund social programs by combating corruption.

He has also committed to supplying addicts with free narcotics to combat drug trafficking.

Despite his rhetoric against corruption, Hernandez is under investigation for allegedly interfering in a trash management tender to benefit a company that his son advocated for. He has disputed his guilt.

The Defense Minister, Diego Molano, told journalists on Sunday afternoon that an investigation was being conducted into killing of an electoral volunteer in Guapi, Cauca province.

The registrar reported that sixty polling stations had to be relocated due to excessive rainfall in certain parts of the country.