Former Chilean president Sebastian Piñera and his wife, Cecilia Morel, cast their ballots in Santiago on Dec. 17. (Gonzale/Epa-Efe/Rex/Shutterstock)

Billionaire conservative Sebastian Piñera won Chile's presidency on Sunday, with center-left opponent Alejandro Guillier conceding the election as Chile followed other South American nations in a political turn to the right.

With 98.44 percent of the ballots counted, Piñera, 68, had won 54.57 percent in the runoff vote, to 45.43 percent for Guillier, a wider-than-expected margin in a race that pollsters had predicted would be tight.

Months of campaigning exposed deepening rifts among the country's once-bedrock center-left, an opening that Piñera, a former president, leveraged to rally more centrist voters around his proposals to cut corporate taxes, double economic growth and eliminate poverty in the world's top copper producer.

In his concession speech at a hotel in downtown Santiago, Guillier called his loss a "harsh defeat" and urged his supporters to defend the progressive reforms of outgoing President Michelle Bachelet's second term.

Many Chileans had viewed the election as a referendum on her policies, which focused on reducing inequality by making education more affordable and overhauling the tax code.

Piñera's supporters cheered the news at his campaign headquarters as the results were swiftly tabulated on a hot and sunny Santiago evening.

Though neither candidate would have marked a dramatic shift from Chile's long-standing free-market economic model, a ­Piñera victory underscores an increasing tilt to the right in South America after the rise of conservative leaders in Peru, Argentina and Brazil.

Piñera painted Guillier, a senator and former TV anchorman, as extreme in a country known for its moderation and likened him to Venezuelan President Nicolás Maduro, a socialist.

But Piñera's own conservative agenda may also struggle, at a time when efforts by his ideological allies in Brazil and Argentina to reduce fiscal deficits by cutting spending have faced political opposition and sparked protests.

After a leftist party made unexpected gains in November's first round, Piñera sought to woo less-well-off voters with proposals such as the creation of a public pension fund to compete with Chile's much-criticized private pension funds, and the expansion of free education.

The race marks a turning point for Chile's historical coalition of center-left parties. The pact fissured under Bachelet, riven by disagreements over policies such as loosening Chile's strict abortion laws and strengthening unions.

Piñera seized on the backlash, campaigning on a platform of scaling back and "perfecting" Bachelet's tax and labor laws, seen by many in the business community as crimping investment at a time when slumping copper prices were weighing on the economy.