UPDATE 2-Argentina's Cristina Fernandez shakes up presidential race with VP pivot

Argentina's Cristina Fernandez de Kirchner will run as a vice presidential candidate in elections later this year, a surprise move by the firebrand former leader who had been widely expected to be the main challenger to incumbent Mauricio Macri. The left-leaning populist, a divisive character in South America's No. 2 economy, said in a video posted on social media on Saturday she would run for the deputy position with former cabinet chief Alberto Fernandez as the presidential candidate.

The unexpected move will shake up an election race many thought would be a choice between Macri's tough market reforms and the more fiery populism of Fernandez, who supported high social subsidies when she ran the country between 2007 and 2015. It also propels Alberto Fernandez, who had not previously been on people's radar as a presidential hopeful, into an election race expected to be tightly fought between Macri and rivals lining up from among the broad Peronist opposition.

Argentines will head to the polls in October, with Macri increasingly under fire amid a biting recession and inflation that has hurt the market-friendly leader in the polls. Cristina Fernandez, who has a strong core following, was seen as the most likely threat to Macri, although many remain wary of turning back to the former leader who also brought in currency controls and raised taxes on farm exports.

"I have asked Alberto Fernandez to lead a team that includes both of us, him as the presidential candidate and me as a candidate for the vice position," Fernandez said in a nearly 13-minute video on her official Twitter account. The decision could carry Alberto Fernandez, who is little known outside Argentina, into the Casa Rosada presidential palace if the pair can win over more moderate members of the Peronist party who have distanced themselves from Cristina Fernandez.

Alberto Fernandez served as chief of staff for former President Nestor Kirchner, Cristina Fernandez's late husband, and for a few months during her first administration. He is considered a moderate within the broad Peronist political flank and is not related to the former president. (Reporting by Adam Jourdan; Editing by Alison Williams and Tom Brown)