"We are working nonstop to resolve the external public debt crisis, the result of a failed irresponsible model that does not work in any country of the world and which left us hostage to the international financial markets," Guzman tweeted.
Fernandez's government, inaugurated on Dec. 10, is set for tough talks with creditors to restructure around $100 billion in debt to avoid a damaging default after former president Mauricio Macri's administration was dogged by economic crisis.
Guzman, a young economist and acolyte of Joseph Stiglitz, has been tapped to lead restructuring talks with private bondholders and other creditors, including the International Monetary Fund (IMF), which agreed to a $57 billion financing package with Argentina in 2018.
Earlier on Friday, Fernandez told journalists that "everything is fine and on track" with the IMF, though there was little to talk about at the moment.
Argentina's debt talks will face their first big test this month with a $277-million payment due on a Buenos Aires provincial bond, seen as a gauge of how the indebted South American nation will handle its creditors.
(Reporting by Cassandra Garrison; Editing by David Gregorio)
