Colombia's peace deal with leftist rebels was on the verge of collapsing in a national referendum Sunday, with those opposing the deal leading by a razor-thin margin with almost all polling stations reporting results, according to AP. Polls taken before the national referendum, in which voters were asked whether they wanted to ratify or reject a deal ending a half century of hostilities with the Revolutionary Armed Forces of Colombia, had pointed to the "yes" vote winning by an almost two-to-one margin. But with 97 percent of polling stations reporting, 50.2 percent opposed the accord while just 49.8 percent favored it â€" a difference of less than 52,000 votes. The government hadn't taken victory for granted after a highly polarized campaign that exposed how steep a challenge it faces implementing the 297-page accord and bringing about real reconciliation. Colombians overwhelmingly loathe the FARC, which the U.S. considers a terrorist group, and many consider provisions in the accord that would spare the rebels jail time an insult to the 220,000 killed and almost 8 million displaced by the long-running conflict. In the past month, ever since the deal was announced in Cuba after four years of grueling negotiations, the government spent heavily on television ads and staged concerts and peace rallies around the country to get out the vote. It even enrolled the help of U2's Bono and former Beatle Ringo Starr. And for the first time in an election, it made ballots available in Braille so blind Colombians could vote. "We don't want anyone to be feeling excluded, because this is an important decision," said Luisa Fernanda Morena, a 30-year-old volunteer who prepared the materials at the National Institute for the Blind. For the referendum to be ratified, at least 13 percent of the electorate, or 4.5 million voters, must cast "yes" ballots. Turnout was low, less than the 40 percent seen in recent congressional elections, a further sign to some analysts that Colombians' enthusiasm for the ambitious accord was lacking. Also potentially affecting turnout, especially along the Caribbean coast, was heavy rainfall from Hurricane Matthew, which had been off the northern tip of South America since Friday. President Juan Manuel Santos urged his compatriots to vote early and take inspiration from Indian independence leader Mahatma Gandhi. "We in Colombia have to adopt this culture of non-violence," Santos said shortly after casting his ballot in a washed-out Plaza Bolivar next to the presidential palace. "All of us can be protagonists in this historic change taking place in our nation." The opposition, led by influential former President Alvaro Uribe, argued that the government was appeasing the FARC and setting a bad example that criminal gangs would seize on. If the "no" vote prevailed, Uribe said, the government should return to the negotiating table, an option Santos had ruled out. The FARC in recent days made an effort to show its commitment to peace is real. Twice this week leaders of the group traveled to areas hit hard by violence to apologize for massacres committed by their troops and discuss with communities how they can compensate victims. "All of us in life have committed mistakes, some with consequences more serious than others," FARC leader Ivan Marquez said Friday at a ceremony in a northern Colombian town where rebels in 1994 disrupted a street party with gunfire, killing 35. "There's nothing to lose in recognizing it. Speaking the pure and clean truth heals the soul's wounds, no matter how deep they are." On Saturday, in the presence of United Nations observers, the FARC voluntarily destroyed 620 kilograms of grenades and light explosives. It also said they would compensate victims with financial resources and land holdings accumulated during the war. Although Santos wasn't required to call for a vote ratifying the accord â€" some of his advisers and the FARC itself opposed the idea â€" the outcome would be binding. Only if it is ratified will the FARC's roughly 7,000 fighters begin moving to 27 concentration zones where over six months they will gradually turn over their weapons to U.N. observers and prepare for their reintegration into civilian life.