The peso dropped 3.34 percent at the open to 45.50 pesos per dollar. It had tripped 3.52 percent lower on Wednesday as uncertainty over a biting recession and high inflation fed investor nervousness about elections in October.

Argentine debt has also being pummeled, with bond yields rising sharply, while the Latin American nation's country risk has leapt to its highest level in five years, far outstripping other similar emerging markets.

Macri's reelection bid is looking increasingly fraught as he struggles to tame annual inflation running above 50 percent and placate a electorate hard-hit by the economic malaise, a volatile peso and rising poverty.

This has spooked markets, concerned about political uncertainty and what that might mean for the country's debt and the possibility of restructuring under a new leadership.

Macri is facing a rising challenge in the polls from arch rival ex-President Cristina Fernandez de Kirchner, seen as a riskier prospect by investors because of her past populist policies. Some polls show her now beating Macri in a run-off.

The president - who struck a $56.3 billion financing deal with the International Monetary Fund last year - has also been forced toward more populist policies, including a freeze on prices for some food staples and services.