Colombian forces have killed 34 rebels in fighting since the ceasefire ended on January 9, while rebels have launched repeated attacks, killed 19 members of the armed forces and halted pumping of crude oil with bomb attacks.
The guerrillas blamed the "prolonged recess" of negotiations on government appeasement of the "far-right" in Colombia.
"It's the first time in my life that I've voted and I do it for peace", said Pablo Catatumbo, a former FARC commander who is assured a senate seat.
He staked his reputation on securing a peace deal with the Farc and launched peace talks with the group two years after taking office in 2010.
Support for their agenda was soundly defeated, with party candidates getting less than 0.5 percent of the overall vote.
Ex Colombian President Alvaro Uribe's Democratic Center Party has won numerous seats in the Congressional Elections for the 106 members House of Representatives and 102 seat Senate, but not an overall majority.
Colombia's FARC, the former guerilla group was transformed by the 2016 peace treaty into a recognised political party with 10 guaranteed seats across the 102 seat Senate and the 166 seat House of Representatives.More news: Bio Leads Samura To A Runoff
But the major winners of the election, a coalition of right-wing forces centered around former president Alvaro Uribe's Centro Democratico party, have led opposition to the peace deal, and what they see as indulgent treatment of organizations involved in atrocious crimes.
Other parties skeptical of the Farc accords, such as Radical Change and the Conservatives, came in second and third. "Many are furious that people with blood on their hands can run for elections". Many Colombians are furious that the group's leaders are not in jail for the human rights abuses and kidnapping campaign they oversaw during the civil war.
And that can only be achieved by talking, he said, adding he hoped the two sides could agree to another ceasefire. "It is not necessarily bad for the peace process that the FARC did not get many votes - the first step is to normalise their participation in politics".
"The mere fact of not applying what has been signed would be enough for this agreement to be ineffective", said Frederic Masse, an expert on the conflict at Colombia's Externado University.
Former rebels have repeatedly raised concerns that they may be assassinated by right-wing paramilitary gangs or drug traffickers, in a replay of about 5,000 targeted killings during the 1980s, when the group first attempted to found the Patriotic Union political party.
Despite political irrelevance and a creeping anxiety about the glacial implementation of the accord, many rank and file Farc members remain committed to peace. "This is what we must stop", Santos said.
The insurgent group announced they would hold a unilateral ceasefire between March 9 and 13 in respect of people who meant to vote in Sunday's legislative elections.