(Reuters) – Former South African president Nelson Mandela remains in a critical condition in hospital after being admitted more than two weeks ago with a lung infection, the government said on Tuesday.

President Jacob Zuma’s office said doctors were doing their best to ensure the “recovery, well-being and comfort” of the 94-year-old anti-apartheid leader who became South Africa’s first black leader in historic all-race elections in 1994.

Madiba, as he is affectionately known, is revered among most of South Africa’s 53 million people as the architect of the transition to multi-racial democracy after three centuries of white domination.

However, his latest hospitalization – his fourth in six months – has reinforced a realization that the father of the post-apartheid “Rainbow Nation” will not be around forever.

A deterioration in Mandela’s health this weekend to ‘critical’ from ‘serious but stable’ has caused a perceptible switch in the national mood, from prayers for his recovery to preparations for a fond farewell.

U.S. President Barack Obama is due to visit South Africa this week as part of a three-country Africa tour, but Zuma said on Monday Mandela’s worsened state of health would not affect the trip.