As they court the evangelicals who have become so crucial to their party, Republican presidential candidates are stepping into the middle of a family fight. Christian conservative activists are more split than ever over whether to keep the movement's focus on abortion, marriage and sexual chastity -- or scrap that approach as too narrow. The founders of the religious right, now in the twilight of their leadership, see even the suggestion of expanding the agenda as a dangerous distraction. In public, and sometimes in personal ways, they are trying to beat back the challenge. "It's an ongoing debate within the...