Mauricio Macri, the mayor of Buenos Aires, has forced presidential frontrunner Daniel Scioli into the first run-off vote in Argentina’s history. Marci — a pro-business, center-right candidate — nearly took the lead from Scioli, who benefits from the support of incumbent President Cristina Fernández de Kirchner.

While initial polls suggested that Scioli was destined to take the lead, Macri’s vote percentage increased and even surpassed Scioli’s before the end of the night. With 97 percent of precincts reporting, Scioli defeated Macri 36.86 percent to Macri’s 34.33 percent. Argentina’s Constitution demands that, should no presidential candidate garner 40 percent of the vote, the top two candidates must face each other in a subsequent run-off vote. Argentines will return to the polls on November 22. This will be the first time in history the run-off will be necessary; in 2003, former president Carlos Menem forced a run-off election against president to-be Nestor Kirchner but decided to end his campaign before the run-off election took place.

Macri is the mayor of the nation’s capital, Buenos Aires, while Scioli is the governor of Buenos Aires province. Macri’s candidate to replace Scioli, María Eugenia Vidal, also defeated the ruling party candidate, signaling a widespread rejection of the Kirchner-friendly Front for Victory Party. Vidal and Macri belong to the Cambiemos (Let’s Change) Party, which has been promoting more pro-business economic politics in light of the economic downturn under Fernández de Kirchner’s term.

In addition to economic problems, Fernández de Kirchner suffered a major blow to her approval ratings following the scandal around the death of prosecutor Alberto Nisman. Nisman was found with a bullet wound in his head in his home on January 18, 2015, the day before he was to testify before the Argentine legislature that he believed Fernández de Kirchner had agreed to a deal with the Iranian government in which Iran would sell Argentina reduced price oil in exchange for protecting the jihadists responsible for the 1994 bombing of the Argentine Israeli Mutual Association (AMIA) building. The AMIA bombing is the deadliest terrorist attack in the history of Argentina, and hundreds of thousands of Argentines took to the streets in January to protest Nisman’s killing. Nisman had drafted an arrest warrant for Fernández de Kirchner before his death.

Macri has promised a number of reforms should he win the presidency, including undoing Fernández de Kirchner’s “protectionist import measures, crippling export taxes, currency controls, levels of welfare support that have become unsustainable with a 7 per cent budget deficit and the nationalization of pensions funds and as well as the national airline and YPF, the energy giant,” The Independent explains.

The surprise run-off announcement generated something of a miracle in the Argentine stock market. Argentine shares on Wall Street rose 22 percent in value in response to the election.

“It is a transcendental and absolute change in Argentine politics, the beginning of a new stage and it means a huge responsibility,” Macri said in an address to his supporters Sunday night. “I hope that many that voted the government because they thought there was not another opportunity, who were giving up, to don’t give up,” he urged.

Macri and Scioli are now working to woo voters who supporters Sergio Massa, the third place candidate who will not be part of the run-off vote. Massa was formally a member of the Kirchnerist movement before defecting and creating his own party, the Renewal Front. “The Renewal Front voter is much further from Macri than from us,” Scioli said on Sunday. “He has the problem, not us.” “I feel the voter of (Sergio) Massa thinks the same we think, that wants a change,” Macri said when asked of Massa’s supporters, 21.34 percent of the vote.

The candidates may debate again before they return to the campaign trail. Scioli told reporters he had called Macri and demanded a one-on-one debate before November 22. A source close to Macri told Argentine newspaper Clarín that he “immediately said yes” when receiving the debate request.