The mayor of Buenos Aires, Argentina appears headed for a run-off, after getting the most votes in mayoral elections widely viewed as a test of President Cristina Fernandez de Kirchner's re-election hopes.

Official results from Sunday's vote are not available, but exit polls indicate the incumbent mayor, Mauricio Macri, and Senator Daniel Filmus, the government candidate hand-picked by President Fernandez, have finished first and second respectively. Filmus is a former education minister.

Pre-election polls had indicated Macri, a businessman and former head of a football club, had a wide lead over his main challenger, but not enough to avoid a run-off July 31.

The capital's 2.4 million voters represent nearly 10 percent of the country's voting population. Analysts are watching Sunday's vote as a gauge of the president's popularity. But they say a defeat for Ms. Fernandez's candidate in Buenos Aires will not hurt her chances of winning re-election to the presidency on October 23.

Under Argentina's electoral system, candidates can win the presidency in the first round with 40 percent of the vote as long as their nearest rival trails by at least 10 percent. A candidate who gets more than 45 percent of the vote wins the presidential election outright.