Following the death of State President Nicolaas Diederichs on August 21, 1978, a new election for the South African head of state was held which pitted former Prime Minister John Vorster, backed by the then-ruling National Party, against former United Party leader De Villiers Graaff supported by the New Republic Party, and Vice-Chancellor of the University of the Witwatersrand, Guerino Bozzoli, supported by the Progressive Federal Party. Wikipedia