SANTIAGO, Chile — Chileans on Sunday elected Gabriel Boric as their next president, entrusting the young leftist lawmaker with helping to shape the future of a nation that has been roiled by protests and is now drafting a new Constitution.
At 35, Mr. Boric will be the nation’s youngest leader and by far its most liberal since President Salvador Allende, who died by suicide during the 1973 military coup that ushered in a brutal 17-year dictatorship.
He will assume office at the final stage of a yearslong initiative to draft a new Constitution, an effort that is likely to bring about profound legal and political changes on issues including gender equality, Indigenous rights and environmental protections.
Capitalizing on widespread discontent with the political factions that have traded power in recent decades, Mr. Boric attracted voters by pledging to reduce inequality and promising to raise taxes on the rich to fund a substantial expansion of the social safety net, more generous pensions and a greener economy.
The president-elect defeated José Antonio Kast, a far-right former lawmaker who sought to portray Mr. Boric as a radical communist who would put Chile on a ruinous path, by destroying one of the region’s most solid economies. Mr. Boric’s coalition includes the Communist Party.
Mr. Kast conceded the race, saying he had called Mr. Boric to congratulate him.
“From now on, he is the president elect of Chile and deserves all our respect and constructive collaboration,” Mr. Kast wrote on Twitter.
With more than 98 percent of ballots counted, Mr. Boric had won more than 55 percent of the vote and Mr. Kast had 44 percent. The margin surprised political observers because recent polls suggested the race was tighter.
“I am going to give the best of me to rise to this tremendous challenge,” Mr. Boric said during a televised video call from the outgoing president, Sebastián Piñera, which continued a tradition in Chilean politics.
Mr. Boric also said that he hoped to unite the nation after a hard-fought race. “I will be the president of all Chileans.”
Mr. Piñera said he was pleased “democracy worked, and you were a part of that.”
The race was the most polarizing and acrimonious in recent history, presenting Chileans with starkly different visions on issues including the role of the state in the economy, the rights of historically marginalized groups and public safety.
And the stakes are higher than in other presidential contests: The incoming president stands to profoundly shape the effort to replace Chile’s Constitution, imposed in 1980 when the country was under military rule. Chileans voted overwhelmingly last year to draft a new one.
Mr. Boric, leader of the leftist coalition Frente Amplio, has been a staunch supporter of the push to update the charter, which was set in motion by a wave of protests in late 2019 over inequality, the cost of living and Chile’s free market economy.
In contrast, Mr. Kast campaigned vigorously against establishing a constitutional convention, whose members Chileans elected in May. The body is drafting a new charter that voters will approve or reject in a direct vote next September.
Members of the convention saw Mr. Kast’s rise as an existential threat to their work, fearing he could marshal the resources and the bully pulpit of the presidency to persuade voters to reject a revised Constitution.
“There’s so much at stake,” said Patricia Politzer, a member of the convention from Santiago. “The president has enormous power and he could use the full backing of the state to campaign against the new Constitution.”
Mr. Kast and Mr. Boric clashed forcefully during the final days of the race, each presenting the prospect of his loss as a catastrophe for the South American nation of 19 million people.
Mr. Boric referred to his rival as a fascist and assailed several of his plans, which including expanding the prison system and empowering the security forces to more forcefully crack down on Indigenous challenges to land rights in the south of the country.
Mr. Kast told voters a Boric presidency would destroy the foundations of Chile’s economy and would likely put the nation on a path toward becoming a failed state like Venezuela.
“This has been a campaign dominated by fear, to a degree we’ve never seen before,” said Claudia Heiss, a political science professor at the University of Chile. “That can do damage in the long run because it deteriorates the political climate.”
Mr. Boric and Mr. Kast each found traction with voters who had become fed up with the center-left and center-right political factions that have traded power in Chile in recent decades. The conservative incumbent, Sebastián Piñera, has seen his approval ratings plummet below 20 percent over the past two years.
Mr. Boric got his start in politics as a prominent organizer of the large student demonstrations in 2011 that persuaded the government to grant low-income students tuition-free education. He was first elected to congress in 2014.
A native of Punta Arenas, Chile’s southernmost province, Mr. Boric made taking bold steps to curb global warming a core promise of his campaign. This included a politically risky proposal to raise taxes on fuel.
Mr. Boric, who has tattoos and dislikes wearing ties, is a departure from the mold of traditional presidential candidates. He has also spoken publicly about being diagnosed with obsessive compulsive disorder, a condition for which he was briefly hospitalized in 2018.
In the wake of the sometimes violent street protests and political turmoil set off by an increase in subway fares in October 2019, he vowed to turn a litany of grievances that had been building over generations into an overhaul of public policy. Mr. Boric said it was necessary to raise taxes on corporations and the ultrarich in order to expand the social safety net and create a more egalitarian society.
“Today, many older people are working themselves to death after backbreaking labor all their lives,” he said during the race’s final debate, promising to create a system of more generous pensions. “That is unfair.”
Mr. Kast, the son of German immigrants, served as a federal lawmaker from 2002 to 2018. A father of nine, he has been a vocal opponent of abortion and same-sex marriage. His national profile rose during the 2017 presidential race, when he won nearly 8 percent of the vote.
Mr. Kast called his rival’s proposed expansion of spending reckless, saying what Chile needed was a far leaner, more efficient state rather than an expanded support system. During his campaign’s closing speech on Thursday, Mr. Kast warned that electing his rival would deepen unrest and stoke violence.
Mr. Kast invoked the “poverty that has dragged down Venezuela, Nicaragua and Cuba” as a cautionary tale. “People flee from there because dictatorship, narco-dictatorship, only brings poverty and misery,” he said.
Antonia Vera, a recent high school graduate who campaigned for Mr. Boric, said she saw electing him as the only means to turn a grass-roots movement for a fairer, more prosperous nation into reality.
“When he speaks about hope, he’s speaking about the long-term future, a movement that started brewing many years ago and exploded in 2019,” she said.
The new president will struggle to carry out sweeping changes any time soon, said Claudio Fuentes, a political science professor at Diego Portales University in Santiago, noting the evenly divided incoming congress.
“The probability of making good” on campaign promises “is low,” he said. “It’s a scenario in which it will be hard to push reforms through.”
Pascale Bonnefoy reported from Santiago, and Ernesto Londoño from Rio de Janeiro.