By Nicolás Misculin and Sarah Marsh
BUENOS AIRES (Reuters) - The presidential campaign of Buenos Aires Mayor Mauricio Macri received a boost on Sunday when his pro-business party took nearly half the votes in a primary election in the Argentine capital he has run for the past eight years.
Macri has built a power base in Buenos Aires, which accounts for nearly 10 percent of the national vote, and is one of three leading candidates for October's presidential election. President Cristina Fernandez is barred from a third term.
In the Buenos Aires primary, the two candidates of his opposition PRO party together took nearly 48 percent of the vote, first official results showed, with returns in from two thirds of polling stations.
Horacio Rodriguez Larreta, whom Macri had backed, ultimately won the internal battle for the PRO candidacy with a 10-percentage point lead over party rival Gabriela Michetti.
The Front for Victory, Fernandez's ruling Peronist party, won just 18.6 percent of overall votes.
Analysts say it is almost certain PRO, which Macri co-founded, will win in the Buenos Aires election on July 5.
"I want to thank Mauricio (Macri), thanks for showing us there is another way of doing politics in Argentina, and that with honesty and dedication we can change peoples' lives," Larreta told his supporters in a television broadcast.
Polls show two thirds of voters want a break from Fernandez's interventionist policies, that critics say have hobbled Latin America's third-largest economy which is now teetering on the brink of recession.
Under the leadership of the 56-year-old former president of the Boca Juniors soccer club, the PRO party has earned a reputation for getting things done in Buenos Aires.
Hundreds of thousands of commuters have been helped by a "Metrobus" his administration introduced on the capital's main avenue, separating bus from car lanes and unclogging both.
School nutrition programs, bicycle lanes, pedestrian malls and parks with health stations where people can check their blood pressure have flourished.
Macri has a 60-percent approval rating in the capital. Together with Buenos Aires state Governor Daniel Scioli of the ruling Front for Victory party, he is leading national polls of presidential candidates.
Macri, the presidential candidate most identified with change, has said he would open Argentina to foreign investment by easing strict trade and currency controls.
"It's quite clear that Mauricio Macri is the real winner this Sunday," said Mariel Fornoni, a pollster at the Management & Fit consulting firm.
(Editing by Stephen Coates)
