Argentine President Cristina Fernandez had successful surgery on Tuesday to remove blood from the surface of her brain and is expected to make a full recovery, a government spokesman said.

Fernandez's illness has sidelined the two-term leader ahead of a key mid-term election. 

"The operation went well," spokesman Alfredo Scoccimarro said.

The president's medical team said that the operation took place without complications and that Fernandez was recovering in the intensive care unit of the same Buenos Aires hospital where the surgery took place.

Argentina President's Health

Fernandez arrives to a hospital in Buenos Aires on Monday ahead of her operation. It's not clear how long she will need to fully recover or when she will resume her duties as head of state. (Pablo Molina/Associated Press)

The surgery came at a time when the government is facing a number of challenges and many people are worried by the country's dominant political force being sidelined.

Congressional elections in less than three weeks are threatening to weaken the governing party's strength, Monday's U.S. Supreme Court rejection of an Argentine appeal makes another debt default more likely, the economy has slowed sharply and Vice-President Amado ​Boudou, who has the reins of power while Fernandez recovers, is under investigation for corruption.

"This is no time to go on automatic pilot," Argentine economist Jorge Todesca said.

Without Fernandez's daily presence, top officials could lack the political authority they need to manage the looming economic crisis, he said.

Not clear when she'll return

The doctors' brief post-surgical report made no reference to how long the president would need to rest or how much Argentines could expect from her in the meantime.

Some outside experts said patients can need as much as three months to recover from such surgeries, and that only time will tell if her still-unexplained head injury caused lasting brain damage. Others said the 60-year-old leader she could be safely back at work within days.

Without knowing private details about her condition, it was difficult to predict.

Many people cheered after the president emerged from surgery. Some had spent all night holding vigil, carrying statues of the Virgin of Lujan, Argentina's patron saint, and messages such as "Fuerza Cristina," urging her to show her strength.

Fernandez had her thyroid glands removed last year after she was diagnosed with cancer, although later tests indicated no cancer was present. Her late husband, former president Nestor Kirchner, died from a heart attack in 2010.

With files from Reuters