MEDELLÍN, Colombia — Iván Duque, a conservative former lawmaker, will be sworn in as Colombia's next president after he swamped his leftist rival in the country's second-round election on Sunday.

Colombia's election authority said Duque — at 41 years old, the country's youngest president-elect for more than a century — had won 54 percent of the popular vote, leading former Bogotá Mayor Gustavo Petro by more than 2 million votes, with nearly all votes counted.

Petro took 41.8 percent, while 4.2 percent of voters cast blank ballots, a popular form of political protest in Colombia.

"A new generation has arrived to govern Colombia with the largest vote in the country's history," Duque said in a victory speech at his Democratic Center party's headquarters in Bogotá.

Petro conceded defeat but pointed to the 8 million Colombians that had voted for his proposals.

"What defeat? Eight million free Colombians making a stand," he tweeted. "There's no defeat here. For now, we won't be in government."

Duque's pro-business platform and hard-line approach to security were attractive to voters during a runoff campaign that pitted hard right against hard left after a first round last month eliminated the more centrist candidates.

Duque led that contest with 39 percent of the vote, falling short of the majority required to avoid a runoff.

Duque, a former lawyer at the Washington-based Inter-American Development Bank, or IDB, who will take office for a four-year term in August, has pledged to cut taxes, lure foreign investors and bolster the military.

He also plans to amend a peace deal signed in 2016 by the government of outgoing President Juan Manuel Santos and leaders of the Revolutionary Armed Forces of Colombia to formally end a five-decade civil conflict that left more than 220,000 people dead and millions more internally displaced.

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