This episode's headline: On the Ground; Allies at Odds; Stem Cell Research; Conversation. ANCHOR: JIM LEHRER; GUESTS: TODD PURDUM; NORMAN PODHORETZ; ANTHONY LEWIS; ROBERT MAC NEIL; CORRESPONDENTS: KWAME HOLMAN; RAY SUAREZ; SPENCER MICHELS; MARGARET WARNER; GWEN IFILL; TERENCE SMITH; KWAME HOLMAN