Argentina's presidential race looks set to go down to the wire, with the first batch of polls showing incumbent Mauricio Macri and center-left challenger Alberto Fernandez neck-and-neck.

Half a dozen polls analyzed by Reuters show the election, a referendum on Macri's painful market reforms to trim the country's debt levels, likely going to a second-round runoff with no clear winner emerging from the first-round vote on Oct. 27.

The polls, from a range of major domestic pollsters, were split over who would win a runoff. All, however, showed no candidate hitting the 45% threshold to win outright in a first round of voting.

"It's like flipping a coin," polling analyst Jorge Giacobbe told Reuters. "That coin is currently still up in the air."

The polls point to tense months ahead for Argentina and its jittery markets, but also suggest both sides will need to make concessions to win over the middle ground of voters, potentially softening any more controversial policies.

Macri, a market-friendly conservative, has seen his popularity hit hard by a recession and swirling economic crisis that dragged down the peso currency last year and sparked near 50% inflation.

The former business magnate has gotten a boost recently from some positive economic signs, including a stronger peso and tempering inflation.

Alberto Fernandez, a surprise candidate for the Peronist opposition, is leading a ticket with former President Cristina Fernandez de Kirchner, a militant populist with an ardent following who many had thought would be the main challenger to Macri.

Pollsters said that with both Macri and Cristina Fernandez unpopular with large swaths of voters, the election may swing on who can win over the middle ground. Alberto Fernandez, who is not related to his running mate, is seen as a moderate voice within the Peronist opposition.

Pollsters Ricardo Rouvier & Asociados, Raul Aragon & Asociados and Tendencias have Fernandez winning both the first round and then the runoff; Management & Fit and Synopsis conversely predict a narrow head-to-head win for Macri after coming second in the first round. 

"It's all about the 13% or 14% of people who don't want to make a decision yet, who are angry with both of them," said Giacobbe, who expects a close runoff.

To prevail in the first round and avoid a runoff, candidates need to obtain 45% or above of the vote or 40% with at least a 10-point lead over second place.

In the polls, centrist Peronist Roberto Lavagna and libertarian Jose Luis Espert appear alternately in a distant third place, unlikely to mount a significant challenge to either Macri or Fernandez.

Read More