This episode's headline: On the Stump; Economic Impact; The Nader Factor; Blood Shortage. ANCHOR: JIM LEHRER; GUESTS: VICE PRESIDENT AL GORE; GOV. GEORGE W. BUSH; JOHN MAKIN; WILLIAM SPRIGGS; MORTON MARCUS; DAVID KENNEDY; SEN. PAUL WELLSTONE; JIM HIGHTOWER; CORRESPONDENTS: FRED DE SAM LAZARO; BETTY ANN BOWSER; SUSAN DENTZER; RAY SUAREZ; SPENCER MICHELS; MARGARET WARNER; GWEN IFILL; TERENCE SMITH; KWAME HOLMAN