Days before she is set to go on trial on corruption charges, Cristina Fernández de Kirchner announced on Saturday that she intends to return to the presidential palace this year, this time as vice president running alongside Alberto Fernández, a former ally with whom she has had an uneasy relationship.



The announcement by Mrs. Kirchner, who governed Argentina from 2007 to 2015 and is currently a senator, stunned Argentine political observers who had widely expected the leftist leader to mount a bid for a third presidential term.

Mr. Fernández served as cabinet chief to Mrs. Kirchner’s husband, Néstor, who took office after a record-breaking default in 2001 left the economy in collapse and who governed during a period of relative prosperity fueled by a commodities boom.

He remained in the role when Mrs. Kirchner succeeded her husband, but stepped down a few months later after a battle between the government and farmers over export taxes.