Buenos Aires (CNN) -- Argentine President Cristina Fernandez de Kirchner is no wallflower when it comes to public speaking.
She's known for passionate proclamations on national television and rapid-fire online posts about her work.
But it's been almost a month since her last public appearance and 33 days since her last Twitter post, prompting critics to question who's in charge of the South American country. Close aides to Fernandez have dismissed such concerns, stressing that she's the one making the government calls.
"The President is present every day, working with us," Cabinet Secretary Jorge Capitanich told reporters earlier this month, according to the state-run Telam news agency.
Fernandez went on medical leave in October so doctors could perform emergency surgery to remove a blood clot on the surface of her brain. She officially returned to work in November and appeared at a series of events in December.
But now, with Fernandez largely out of public view once again, speculation has surged about her whereabouts, and her health.
"If we hadn't had the President's illness just a few months ago, one would discard it. But the problem is the rumor has been established, and the sense of uncertainty of not knowing why," said Orlando D'Adamo, director of the Center of Public Opinion at the University of Belgrano in Buenos Aires. "Is it a political strategy? Is she making room for a new candidate for 2015? Is it because she does not want to face difficult situations for the government? We do not know."
Others think Fernandez is taking a break to take care of her health and not face a similar fate as her husband, former President Nestor Kirchner, who died in 2010 after suffering a heart attack.
"I think she does not want to repeat that story," said Enrique Zuleta, another political analyst.
As Argentina has faced high inflation and other challenges in recent weeks, Capitanich was the public face of the government.
On the streets of Buenos Aires, residents say they have felt the President's absence.
"There are many problems that require a solution, and there is no clear response from her," worker Gabriel Blanco said.
Merchant Nelida Jorquera said she was worried about the situation.
"But I think she is a serious person, and she would not deceive the people," she said.
CNN's Jose Manuel Rodriguez reported from Buenos Aires. CNN's Catherine E. Shoichet reported from Atlanta.