MEDELLIN, COLOMBIA – APRIL 2: Former President of Colombia, Álvaro Uribe, greets supporters during the demonstration against the Peace Process in Medellin, April 2nd, 2016. People took the streets of Colombia against Government polices including the the way the peace treaty is being handle. (Photo by Eduardo Leal For The Washington Post via Getty Images)

BOGOTÁ, Colombia – When Wilson Córdoba was growing up in rural Colombia, his 90-minute walk to school through the forest was a perilous one: He and his friends had to pass illegal armed groups that fought in the area and recruited many of his friends to join their ranks. “The psychological pressure was immense,” he said. When he got home from school, there was no playing outside – rebels from the Revolutionary Armed Forces of Colombia (FARC), paramilitaries, and the Colombian army fought over territory, sometimes leaving dozens dead and disappeared in a single day. “I didn’t have a childhood,” he said.

Córdoba’s experience is not unlike that of many rural Colombians who were terrorized or displaced during the country’s half-century of armed conflict against the FARC, which first rebelled in the 1960s over land inequality; later, it would turn to kidnapping, narcotrafficking, and violence, earning it a classification as a terrorist group by the European Union and the United States. The right-wing paramilitary groups that rose up to fight the FARC were even worse, carrying out massacres and displacing millions of people. Both groups raped, disappeared, assassinated, tortured, and threatened civilians. After more than 50 years of war, Colombia’s total displaced population rivals that of Syria.

But on June 23, officials with the government and the FARC took an important step toward ending the conflict by signing a permanent cease-fire agreement. After four years of negotiations, the deal will put an end to hostilities that saw the government lose two-thirds of the nation’s territory in the early 2000s – one-third to the FARC and one-third to paramilitaries, said Colombian President Juan Manuel Santos.

Santos announced that by July 20, the two sides will sign a finalized peace deal. He has also promised to hold a plebiscite (at a date to be determined) to allow Colombians to register their approval. Although the plebiscite isn’t legally binding, Santos hopes it will counter claims from the opposition that he has been unilaterally negotiating the country’s future with a feared and hated rebel group. But a “no” vote would send both parties back to the drawing board. The decision of whether to hold a plebiscite is before the country’s Constitutional Court, which will probably approve it.

If the peace deal succeeds, however, Santos will have brought the longest-running war in the Western Hemisphere to an end. But not everyone is celebrating – not even Córdoba, who was elected to Congress in 2014 as a member of the Centro Democrático, the center-right party standing in Santos’s way. The Centro Democrático says the deal gives impunity to the FARC and will allow it to hold on to its arms and drug money while participating in Colombian politics. New violence, the party says, will be the consequence.

Whether through the plebiscite or later in the 2018 presidential elections, the Centro Democrático stands ready to capitalize on the widespread mistrust of the peace process; Santos’s approval ratings among urban Colombians dropped to 21 percent in May. In the same poll, 66 percent of urban respondents said they believed the peace negotiations would produce a bad deal. Finalizing the deal appears to have given him a bump, though – Santos’s approval ratings rose to 30 percent in July. The majority of likely voters now say they will vote for the plebiscite, though the Centro Democrático will have time to chip away at its legitimacy and encourage their supporters to abstain.

Santos now must convince the public – particularly those who lost their homes and family members in the war – that the country has more to gain from an imperfect deal than from continuing to fight or delay. At a recent economic forum, the president went so far as to suggest that if the referendum failed, war would break out again. He said he had “ample information” that the FARC is “preparing to return to war, even an urban war.” Santos was probably trying to convince the public by making the stakes clear, but his opponents have portrayed it as a blunder – an attempt to “blackmail” the public.

Santos has staked his legacy on the deal, sacrificing political and personal ties along the way. From 2006 to 2009, he served as minister of defense under President Álvaro Uribe, who left office with a 75 percent approval rating thanks largely to his tough military action against the rebels. In 2010, Santos captured the presidency easily, riding the wave of Uribe’s immense popularity and promising to continue his hard-line policies. But once in office, Santos aggressively pursued peace, triggering a falling out with Uribe, who in 2013 founded the Centro Democrático.

The Uribistas’ opponents, on the other hand, say the Centro Democrático’s objections to the process are disingenuous. Iván Cepeda, a leftist senator who has written a book about “Uribeism,” tweeted on June 15 that the Uribistas “should take off the mask and say openly and directly that they don’t want peace.”

Amid the ongoing violence, Uribistas like Federico Hoyos say they’re offended by the idea that their party doesn’t want peace. The youngest member of Congress, Hoyos says he wants a durable, legitimate peace, not one that treats the FARC as “legitimate political actors.” He says after years of kidnappings, massacres, and child recruitment, the FARC has forfeited the right to be an equal negotiating partner. Hoyos and the Uribistas often point to the FARC’s designation by the United States and the European Union as a terrorist organization as a reason that the peace talks are inherently flawed: A peace deal happens after a war between states; terrorists like the FARC are defeated. “Why should I, when the only thing I have in my backpack is pens and an iPad, be seated next to a guy that might have a gun in his backpack?” Hoyos asks, balking at the idea that FARC members will be allowed to run for office.

Though Uribe and his followers have vehemently opposed the idea of FARC members serving in Congress, leaked documents in 2014 showed that when he was president he attempted a peace negotiation with the FARC that would have offered them both congressional seats and protection from extradition.

Minster of the Interior Juan Fernando Cristo disputed this, writing in an email that the selection process for justices had not been established yet but that they would have to meet the same requirements as those who serve on the Supreme Court, in addition to having expertise in international human rights or conflict resolution. He added that the selection process would have to “give confidence to the Colombian people and offer complete guarantees of impartiality and independence.”

The Centro Democráticos are not the only ones to raise the alarm about the tribunals. In 2015, Human Rights Watch said the tribunals would “make it virtually impossible that Colombia will meet its binding obligations under international law to ensure accountability for crimes against humanity and war crimes.” Others, like former Constitutional Court Magistrate Rodrigo Uprimny have argued that flexibility is necessary on matters of justice in order to secure the end of the war.

However, the FARC have sought to go further in the peace negotiations and achieve land redistribution – one of the insurgency’s original objectives. In 2012, the government and the FARC compromised by agreeing that legal private property would not be touched, but public lands and territory confiscated from drug traffickers would be redistributed. The deal they made clearly upsets Federico Hoyos. He said landowners in Antioquia, the northwestern department (a Colombian territorial division) he was elected to represent, fear that the government is coming for their land. “In my department, people will not let this happen,” Hoyos says. “This might be the birth of new violence because if they’re dealing with the land ownership with the FARC, a lot of people in this country are going to do whatever it takes to protect their land.”

In February, authorities arrested Uribe’s brother for allegedly leading a death squad known as the Twelve Apostles, which is accused of planning assassinations at the Uribe family ranch during the 1990s.

Sen. Alfredo Ramos, a Centro Democrático, is the son of another Uribista politician who was arrested for alleged paramilitary ties in 2013 while campaigning for the party’s presidential nomination. In a Skype interview in June, he told Foreign Policy that his father, who is still in prison but has not been convicted, had been accused by false witnesses and that his father and other Centro Democráticos had been the victims of political persecution. While he can’t prove that Santos and his government are deliberately persecuting the Centro Democráticos, he says the party believes Santos is “trying to accelerate” prosecutions against the party to diminish its credibility.

Whether or not the Santos government is truly targeting the Uribistas, the investigations into politicians with alleged links to paramilitaries have been going on since before his election. Uribe’s credibility has taken a hit; now that he is a senator, his approval rating has dropped below 50 percent. But perhaps the real test of his party’s credibility will be whether it can persuade Colombians to vote against the peace deal in the plebiscite, or to sign their “civil resistance” petition against the deal.

Ramos thinks his party can turn the Colombian population in the Centro Democrático’s favor. He says the Colombians felt “blackmailed” by Santos after his comments about the likelihood of the FARC returning to war if the plebiscite fails. “The more the population of Colombia feels blackmailed, the more support President Uribe will have in the future,” he predicted.

Ramos may be proven wrong – now that the FARC has agreed to lay down its weapons, confidence in the peace process could skyrocket, the plebiscite could pass easily, and the influence of Uribe and the Centro Democrático could fade. Many Colombians, after all, doubted that the four-year process would lead to a deal at all.

However, Ginny Bouvier, a Colombia expert at the U.S. Institute of Peace, said it is difficult to predict how the electorate will vote in a plebiscite. “Uribe … has plugged into the deepest fears of Colombians,” she says. “The question is whether the emotion of peace will outweigh the emotions of fear and of vengeance.”

If the plebiscite fails, it would be “back to the drawing board,” Bouvier says. But even if it passes, the first five years following the singing of a peace deal are perilous. Various academic studies have found that between 40 and 50 percent of countries relapse into war after a peace deal, with the riskiest period occurring just after the signing, as the tough work of implementation begins.

Another factor that could drive former FARC combatants back to violence – and one of the main post-conflict dangers – is the use of violence against demobilized FARC combatants by “those who remain violently opposed to their participation in politics,” says Cynthia Arnson, who heads the Wilson Center’s Latin America program. “That could really cause things to unravel if it happens on a significant scale,” she adds. The largest neo-paramilitary group, or “criminal band,” promised on Monday that they would not attack demobilized FARC soldiers, but the risk of breakaway factions remains.

When an earlier, more tenuous peace process began in the 1980s, thousands of members of the FARC’s then-political party, the Patriotic Union, were slaughtered by paramilitaries, members of the armed forces, and criminal groups. The FARC itself has said it fears this outcome. And it is not hard to see how precedent could lead individuals to once again take up arms, even if the FARC sticks to its word and does not return to war.

Córdoba insists that this is not what he wants. “Who more than me, having lived what I’ve lived, wants now, tomorrow, for it to be signed and for us all to have the tranquility of a peace process?” Córdoba asked as he sat in the salon of the Colombian Congress in April. “We don’t make objections because we don’t want peace. We want to help the peace process along so that it is what all us Colombians are hoping for – effective and forceful.”

Megan Alpert’s reporting in Colombia was made possible by an Adelante fellowship from the International Women’s Media Foundation.

Photo credit: Eduardo Leal for the Washington Post via Getty Images

Correction, July 18, 2016: A previous version of this article misspelled Colombian Sen. Iván Cepeda’s last name.

Correction, July 20, 2016: A previous version of this article incorrectly stated that Álvaro Uribe enjoys immunity from prosecution as a former president. Because he holds political office, Uribe is subject to a special jurisdiction that governs how and by whom he can be investigated and tried. The sentence referencing this has been removed.