They also offered their "wishes and prayers" to the ailing leader, who remains in a South African hospital battling a respiratory infection. 

The president was unable to meet with Mandela, the first black president of South Africa and an anti-apartheid icon, during his trip there last month, due to health concerns.

But the Obamas did meet with Mandela's family while visiting South Africa, and also took a tour of Robben Island. Mandela was jailed for 18 years at the prison there.

Obama said then that he looked forward to showing his daughter the prison to “teach them the history of that place and this country, and to help them understand not only how those lessons apply to their own lives."