Buenos Aires Mayor Mauricio Macri won re-election on Sunday, beating Argentine President Cristina Fernandez's candidate by nearly 30 percentage points and raising doubts about her invincibility in an October vote. Macri won 64.3 percent of votes compared with Peronist senator Daniel Filmus's 35.7 percent, official results showed. This meant support for the center-right leader rose more than 3 percentage points from 2007, when the two men first faced off. Filmus's defeat was largely expected in a capital city where anti-Peronist feeling runs deep. But this result combined with a stinging setback in a key provincial election last weekend could hurt Fernandez's chances of re-election on Oct. 23, which had been viewed as a foregone conclusion due to her wide lead in polls. "This doesn't change the scenario substantially ... in 2007 (the ruling party suffered) a series of electoral defeats and Cristina Fernandez went on to win with 46 percent of votes," politic al analyst Graciela Romer told local television. There is an idea taking hold, however, that it's not so clear a Fernandez victory is inevitable," Romer said. Filmus's performance gives a sense of how Fernandez may fare in the capital during an upcoming nationwide primary and again in October, when she must garner at least 40 percent of the vote to win in the first round. Filmus told supporters he took "personal responsibility" for the defeat and vowed to analyze what went wrong. Interior Minister Florencio Randazzo chalked up the center-left government 's defeat in Buenos Aires to the traditionally anti-Peronist electorate. Macri-a millionaire who used to run the nation's best-known soccer club, Boca Juniors-planned to run for president but dropped out of the race in May to ensure his party kept control over city government. He told supporters he hoped to meet with all the presidential contenders-including Fernandez-but said his party would not necessarily back any of them. Opposition to Fernandez has been fragmented, helping her re-election prospects. Under Argentina's electoral system, candidates can win the presidency in t he first round with 40 percent of votes as long as their nearest rival trails by at least 10 percentage points. Support above 45 percent guarantees a first-round victory. Last weekend in Santa Fe province, a farming bastion, the government's candidate came in an unexpectedly distant third in the gubernatorial race and the candidate representing Macri's PRO party made a strong second-place showing. Voters will cast their ballots in Cordoba province next weekend, the last election before the Aug. 14 primaries, which are viewed as a dress rehearsal for October since no party is fielding more than one presidential candidate. Santa Fe, Cordoba and the city of Buenos Aires are home to almost a quarter of Argentina's 40 million people. "These results have changed the political climate. But we have to wait until August 14th to analyze the vote in a nationwide context," said Fabian Perechodnik of Poliarquia political consultancy.