Conservative opposition challenger Mauricio Macri won Argentina's presidential election on Sunday, bringing to an end more than a decade of free-spending leftist populism with a promise to open up the ailing economy to investors.
Weary of outgoing President Cristina Fernandez's confrontational style and protectionist policies that hobbled growth, Argentines warmed to Macri's pledges to liberalize Latin America's third biggest economy and stamp out corruption.
With the count nearly completed, Macri won 51.5 percent of the vote in the run-off election to 48.5 percent for ruling party rival Daniel Scioli, a smaller margin of victory than expected.
Macri's supporters swarmed around the iconic Obelisk in the heart of Buenos Aires's theater district as passing cars blared their horns in celebration.
"This is the beginning of a new era that has to carry us toward the opportunities we need to grow and progress," Macri told supporters at his headquarters, which pulsed with Latin music and was festooned with white and sky-blue balloons, the colors of the Argentine flag.
The victory marked a stunning turnaround for the two-term mayor of the capital Buenos Aires, who had looked a distant prospect just a month ago. He will be sworn in Dec. 10.
The upset ends 12 years of Peronist-run governments under Fernandez and her late husband Nestor Kirchner, a power couple who emerged after Argentina's epic economic collapse in 2001-02.
Painted by Scioli as a neoliberal bent on placing the interests of big business before workers, Macri had trailed his rival in opinion polls throughout months of campaigning.
However, he blindsided Scioli and the ruling Front for Victory Party with a strong performance in the first round of voting last month and quickly became the favorite as pollsters showed swing voters rallying behind his "Let's Change" alliance.
"There's been so much corruption and the economy has been poorly managed," said Romina Casela, 41, who swung behind Macri for the second round. "I have faith Macri will be an honest politician."