After 52 years of a hard fought and bloody civil war, the Latin American nation may be ready to bury the hatchet with the FARC, while an influential former president is leading a campaign against the peace deal.
FARC rebels and the people of Colombia are set to clear the final hurdle in the nation's long race for peace.
The landmark referendum, which is taking place on Sunday, will bring an end to a 52-year-long war and allow the Revolutionary Armed Forces of Colombia (FARC) to re-enter society and form a political party.
Colombian President Juan Manuel Santos is asking his people to support the peace accord he signed last week with the rebel commander known as Timochenko. Voting closes at 4 pm local time (2100 GMT) and results from the simple "yes" or "no" ballot are expected by early evening.
FARC has agreed to turn in weapons and fight for power at the ballot box instead of with bullets, after four years of peace talks in Havana concluded last week.
Recent polls show about two-thirds of voters are likely to ratify the internationally applauded peace agreement.
Influential former President Alvaro Uribe has led the "no" camp, arguing that rebels should pay for crimes in jail and never be given congressional seats. But most Colombians, including even some who see the accord as too soft on the FARC, seem convinced that an imperfect peace is better than more war.
"Even one less death is enough of an argument," said Sandra Guevara, a 42-year-old secretary. "I'm voting yes because I'm betting on hope, to guarantee my son can see a better country."
Under the accord, the FARC - which began as a peasant revolt in 1964 - can compete in the 2018 presidential and legislative elections and has 10 unelected congressional seats guaranteed through 2026.
While the number of seats is not enough to sway legislation, some are still outraged.
"The president has given the guerrillas the ability to be in government. He's sold out the country," said 66-year-old Bogota housewife Fanny Castro, whose son-in-law is in the army. "We have to vote no or we'll have the guerrillas on top of us."
For decades, the FARC bankrolled the longest-running conflict in the Americas through kidnapping and extortion, spreading a sense of terror that left few Colombians unaffected. The conflict claimed more than 220,000 lives and displaced millions of people.
If the peace accord is approved on Sunday, Santos will likely turn his focus toward a much-needed tax reform and other measures to compensate for a drop in oil income, as well as possible talks with the smaller National Liberation Army (ELN) rebel group.