Former President Cristina Fernandez has returned to Argentina's political stage, launching a new party and promising to fight the economic policies of her conservative successor.

The woman who governed Argentina from 2007 to 2015 told a rally in Buenos Aires Tuesday that the party would be called Citizens Unity and would compete in October's midterm elections.

Current President Mauricio Macri was elected vowing to clean up corruption and regenerate the economy with a pro-business government that would reverse some of the policies of the left-leaning Fernandez.

Fernandez, who has been critical of Macri's budget cuts, did not say if she would run for a senate seat, as has been speculated.

"We need to put a limit on this government to stop the (economic) adjustment," she told thousands of supporters.