A look at key issues in the health care debate:

THE ISSUE: Which former presidents have attempted comprehensive health care reform and why hasn't anyone succeeded?

THE POLITICS: Many have tried. Only Lyndon Johnson achieved transcendent reform, with passage of Medicare and Medicaid protecting the elderly and poor, but universal coverage has been an elusive goal for over a century. Franklin Roosevelt promoted national health insurance but gave priority to jobs and retirement security during the Depression. Harry Truman fought for a single insurance system to cover everyone but ran into Republican opposition and the cries of "socialized medicine" heard again today. Perhaps if not for the Watergate scandal that destroyed his presidency, Richard Nixon might have become the Republican president to have given the country universal coverage with his plan to expand the employer-based system and widen protection for the poor. Bill Clinton's effort foundered in its complexity and under assault from opponents.

WHAT IT MEANS: Although Democrats have generally been the drivers of health coverage expansion, having that party in control of the White House and Congress is no guarantee of success, as the experiences of FDR, Truman and Clinton teach. Moderates and liberals have long tussled over the best path, at times splintering support to a point where nothing was done. Republican support for expanded coverage has waxed and waned, perhaps peaking in the Nixon years, according to a review of health reform history by the Kaiser Foundation. Ideological splits, fierce lobbying, dispersed powers in Congress and the sheer scale of the task have proved daunting. LBJ tapped a strong Democratic majority, a talent for arm-twisting lawmakers and the support of health insurers and hospitals _ but not the American Medical Association _ in achieving Medicare and Medicaid in 1965.

_ Cal Woodward