THE White House said on Monday it will nominate Delano Lewis, a former National Public Radio director, to be the United States’ ambassador to South Africa. Lewis served as assistant director of operations for the Peace Corps in Nigeria in the 1960s and then as Uganda’s Peace Corps director. Later, he became director of Peace Corps activities in eastern and southern Africa. The Kansas native, a lawyer by profession, headed a telephone company in Washington for some 20 years before becoming NPR’s chief executive officer in 1998.