Argentine opposition presidential candidate Mauricio Macri is criticizing some leftist governments in South America.

Several opinion polls now have Macri as the front-runner in the presidential runoff election later this month.

He has campaigned on free-market ideas and describes his vision of governing as "21st century development" as compared to "21st century socialism."

Macri told a gathering of international reporters Tuesday that despite differing ideologies, he would not have a problem working with left-leaning leaders like Brazilian President Dilma Rousseff.

But he expressed concern about Venezuela's socialist administration, saying he was concerned about opposition leaders who have been jailed under Venezuelan President Nicolas Maduro. Macri said that if the leaders are not liberated, as Argentina's president he would push to remove Venezuela from the South American bloc known as Mercosur.