Nelson Mandela still in 'serious but stable' condition

Nelson Mandela in 2008. The former South African President remains in "serious but stable" condition.

The South African government said former President Nelson Mandela remained in "serious but stable" condition Tuesday.

The news came as the 94-year-old anti-apartheid leader spent his fourth day in a Pretoria hospital battling a lung infection.

A statement from President Jacob Zuma's office said the government was monitoring Mandela's progress and "doing [its] best to make Madiba better," referring to his clan name.

Mandela's ex-wife Winnie Madikizela-Mandela and other relatives have been visiting the ailing leader who remains in intensive care.

On Tuesday, his two daughters visited Mandela, perhaps a sign of his deteriorating condition, according to CBS News.

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This is Mandela's fourth time back in the hospital since last December, and he was most recently released in April after being treated for pneumonia.

Back in December, Mandela spent 18 days in the hospital for both a lung infection and gallstones.

On Tuesday, a group of South African children sang outside his home in Johannesburg to wish him well.

The Rainbow Hill Christian School students sang, "we love you Mandela ... get well, get well," an example of the nation's deep love for this anti-apartheid icon and national hero.

Mandela spent 27 years in prison and was later elected as the country's first black president in 1994. His work helped end the system of apartheid in South Africa.