The conservative mayor of Argentina's capital decided Saturday not to challenge populist President Cristina Fernandez for the presidency and will seek re-election to his post instead.

Mayor Mauricio Macri and Argentina's president are bitter foes, but opinion polls suggest he lacks the support needed to unseat Fernandez as long as other rivals stay in the race for the October presidential election.

"After much reflection and debate, I feel and I'm convinced that the best place from where I can serve is the city of Buenos Aires," said Macri, a former president of the Boca Juniors soccer team.

Polls indicate Fernandez lacks majority support in Argentina, but might easily win re-election in the first round against a divided opposition.

Macri's exit leaves Congressman Ricardo Alfonsin and former President Eduardo Duhalde as her leading challengers. Macri called on them Saturday to find ways of working together to unseat the president.

"Without unity, it will be very difficult to build a better society," Macri said.

The presidential election is Oct. 23, but a primary vote Aug. 14 has taken on more importance for those who hope to change the government for the first time since Fernandez's predecessor and husband, the late Nestor Kirchner, took office in 2003.

By law, all candidates must run in the unified primary election, where Argentine voters can choose any candidate they like irrespective of party affiliation. That means the primary will show better than any poll which opponent has the best chance of unseating Fernandez. And that will increase pressure on the others to drop out.

Macri's decision to run again for Buenos Aires mayor is a calculated risk because Fernandez is expected to throw a great deal of support behind whomever she picks to run against him in the capital. Two government ministers and a leading capital politician are among the ruling party's possible choices. She is expected to decide between them next week.


Michael Warren can be reached at http://twitter.com/mwarrenap