BOGOTA, Colombia Colombian voters appear to have rejected a peace deal with the FARC rebels by a razor-thin margin in Sunday’s national referendum, delivering a major shock to the war-torn country.

The government has yet to concede defeat. But with almost all votes counted, the results look irreversible.

With more than 99 percent of voting stations reporting, those opposing the deal lead with 50.2 percent, compared to 49.8 percent for those backing the deal — a difference of less than 59,000 votes out of 13 million counted.

Colombia’s president has recognized the referendum defeat, and said the cease-fire to remain in place.

The leader of the Revolutionary Armed Forces of Colombia is reiterating the rebel group’s willingness to continue working toward peace following what appears to be a national referendum’s shocking rejection of its accord with the government. 

Speaking to journalists in Havana after Sunday’s referendum results, the FARC leader known widely by his nom de guerre Timochenko referred to the FARC as a political movement instead of a rebel army.

He said he regrets that what he calls “the destructive power of those who sow hatred and rancor have influenced the opinion of the Colombian population.” He says the FARC will keep working to build a stable peace.

In his words, “Peace will triumph.” 

The shock outcome, comparable to Britain’s decision to leave the European Union in the Brexit vote, opens an uncertain outlook for the peace accord that took four years to negotiate. It’s also a major blow to President Juan Manuel Santos, who has staked his presidency on putting an end to a half-century conflict that killed 220,000 and displaced almost 8 million.

Opposition to the accord, 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.

But that is an option that Santos has ruled out. It’s unclear what options the government has to save the accord. The FARC, in a cryptic message, made no indication it intends to resume fighting.

“The love we feel in our hearts is gigantic and with our words and actions will be able to reach peace,” the rebels said in a message published on Twitter as the “no” vote looked headed to victory.

The highly polarized campaign exposed how steep a challenge the government would face 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 considered provisions in the accord that would spare the rebels jail time an insult to victims of the long-running conflict.

FARC leaders, including Timochenko and Ivan Marquez, sat in leather recliners at Club Havana, once Cuba’s most exclusive beach club, watching the results on a flat-screen TV. Initially the atmosphere was festive, with the guerrillas laughing and joking while snacking on cheese-and-olive hors d’oeuvres, smoking cigars and visiting an open bar. The mood soured as results came in, and the rebel commanders talked in hushed tones on cellphones, conferred quietly and asked journalists to leave the room to await a formal statement.

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. Turnout was especially affected along the Caribbean coast, where support for the government is highest, as a result of heavy rainfall from Hurricane Matthew, which made it impossible to set up a few polling stations in La Guajira peninsula.

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.

Santos had 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 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 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 — some of his advisers and the FARC itself opposed the idea — 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.