Pot-banging activists, estimated to number about 700,000, demonstrated Thursday against what they say is her growing authoritarianism and out concern that she could remove constitutional term limits so she could remain in power, Britain's Daily Telegraph reported Friday.
Fernandez won a second term in 2011 with 54 percent of the vote. The constitution limits presidents to two consecutive four-year terms.
Union leader Luis D'Elia called the demonstration "destitute," saying the protesters were part of a wealthy elite that offers "no viable alternative."
Anibal Fernandez, a Cristina Fernandez supporter in the Senate, said the march was funded by the far right.
Organizers called Thursday's march "8N," for Nov. 8, as a response to a government campaign called "7D," representing the Dec. 7 deadline for Clarin, Argentina's biggest media group, to sell assets under a controversial anti-monopoly law opponents said is part of a strategy to control the press.
A law passed last week lowered the voting age to 16, which observers said could help the president, popular among young people, gain the two-thirds parliamentary majority in next year's mid-term elections that would be needed to reform the constitution.
More than 128 lawmakers signed a petition against another re-election for Fernandez, the Telegraph said.
"[This] is the start of a dictatorship," said Elisa Carrio, an opposition lawmaker.