Argentine President Cristina Fernandez's governing bloc took a drubbing in Sunday's midterm elections, shrinking her congressional majority and snuffing out chances of a constitutional change to allow her a third term.
Opposition leader and the president's former cabinet chief Sergio Massa beat out the president's handpicked candidate in the country's largest voting district, Buenos Aires province.
Massa, the mayor of the affluent town of Tigre, is widely expected to be a presidential candidate in the 2015 presidential election.
Some lawmakers had wanted a constitutional amendment to allow the president to run for a third time, but the poor showing by Fernandez's branch of the Peronist party has dashed those hopes.
The 60-year-old president was not able to campaign for her congressional candidates after an operation earlier this month to remove blood from inside her skull and to relieve pressure on her brain.
Her condition may have come from hitting her head during a fall in August.
President Fernandez, who has been in office since 2007, had her thyroid glands removed last year after she was diagnosed with cancer, although later tests indicated no cancer was present.
Her husband, former president Nestor Kirchner, died after a heart attack in 2010.