The president of Colombia was awarded the Nobel Peace Prize on Friday for pursuing a deal to end 52 years of conflict with a leftist rebel group, the longest-running war in the Americas, just five days after Colombians rejected the agreement in a shocking referendum result, reports The New York Times.

The decision to give the prize to the Colombian president, Juan Manuel Santos, may revive hopes for the agreement with the Revolutionary Armed Forces of Colombia, or FARC, with whom the country has been waging the last major guerrilla struggle in Latin America.

Mr. Santos said he was told of the Nobel committee’s decision by his son Martín, who woke him before dawn on Friday. The winner dedicated the prize to his fellow Colombians, especially the victims of the long conflict, and called on the opponents of the peace deal to join him in securing an end to hostilities.

“I invite everyone to join our strength, our minds and our hearts in this great national endeavor so that we can win the most important prize of all: peace in Colombia,” he said alongside his wife during his first public appearance since the Nobel announcement.

Colombian voters threw out the peace deal just days after the government had invited world leaders to a celebratory signing ceremony, leaving its fate — along with Mr. Santos’s legacy — in limbo. Despite the setback, the Norwegian Nobel Committee recognized Mr. Santos “for his resolute efforts to bring the country’s more than 50-year-long civil war to an end.”

Other winners of 2016 Nobel Prize are JapaneseYoshinori Ohsumi, Physiology or Medicine; David J. Thouless, F. Duncan M. Haldane and J. Michael Kosterlitz, Physics; and Jean-Pierre Sauvage, J. Fraser Stoddart and Bernard L. Feringa, Chemistry

In announcing the award, Kaci Kullmann Five, the chairwoman of the committee, commended Mr. Santos for starting the process, even as she acknowledged that the people of Colombia had rejected the outcome.

She said she hoped that awarding the prize to Mr. Santos would act as a spur for a future agreement. “The committee hopes that the peace prize will give him strength to succeed in this demanding task,” she said. “Further, it is the committee’s hope that in the years to come, the Colombian people will reap the fruits of the reconciliation process.”

News of the award stirred excitement on Friday in Colombia, where Mr. Santos is the second man from his country to win a Nobel Prize, after novelist Gabriel García Márquez, who won the literature prize in 1982. Even some who had opposed Mr. Santos in the peace deal offered him well wishes, though they quickly spun the news to their own ends.

“I congratulate President Santos for the Nobel,” said Álvaro Uribe, Mr. Santos’s predecessor as president, who led the campaign against the deal. “I want him to lead to change these peace accords that are damaging to democracy.”

Others saw the prize as a blow to opponents like Mr. Uribe. “It’s a call to all those who have, through deception, wanted to throw this process to the ground — that they stop this and that they join this national reconciliation,” said Ivan Cépeda, a senator who was involved in the negotiations.

The prize appeared to breathe life into hopes among supporters that a deal could yet be clinched. “This has given us a boost to push us to keep working for peace,” Silvia Berrocal, the leader of a group backing the deal, said on a radio station Friday morning.

The committee members, whose deliberations are conducted in strict secrecy, have a reputation for surprises, and this year was no exception. While Mr. Santos had been mentioned as a possibility, to many the leading candidate was the White Helmets volunteer search-and-rescue group in Syria. On Friday, its proponents expressed their disappointment on Twitter, even as the group itself sent a note of congratulations to Mr. Santos.

A United States-trained economist from a wealthy family in Bogotá, the Colombian capital, Mr. Santos rose to power as the country’s defense minister under Mr. Uribe. In that capacity, he organized an intense counterinsurgency campaign that diminished the FARC and wiped out many of its commanders.

As president, Mr. Santos staked his legacy on ending the war. The peace accord, announced in August, was the culmination of four years of negotiations in Havana, as the Colombian government and the rebels worked their way through a series of impasses.