While it is welcome, the shift of policy by U.S. Senate Majority Leader Bill Frist is far from the last word on efforts to open up stem-cell research in the United States.

Frist has signaled his interest in legislation that would allow research on stem cells from embryos that otherwise might be discarded by fertility clinics.

This is a substantive advance over current federal policy, which allows research only on a limited number of stem-cell lines that have proven to be seriously inadequate.

Frist's position, which might help sway other Republicans and even the White House, is also more in line with a position already taken by the House.

The Senate leader's rhetoric was spot-on: Embryonic stem cells, he said, "have specific properties that make them uniquely powerful and deserving of special attention in the realm of medical science."

In theory, such cells have the capability of becoming any kind of human tissue, thus opening the possibility of new therapies for everything from Alzheimer's to Parkinson's disease.

While this "technology" has yet to be proven, it holds tremendous promise. Other nations, including South Korea, are racing ahead with cutting-edge research in this area.

The United States, with its vast wealth and intellectual potential, should not be left out of this chase. While the political and social issues are daunting, there is no doubt that the scientific promise of stem-cell research is worthwhile.

Unfortunately, despite his recent softening of position, Frist has not yet promised or scheduled a vote on this new approach. And he continues to push for research that avoids the use of embryonic stem cells altogether.

It is imperative that Sen. Frist schedule debate and a full vote on this legislation directly after the congressional Labor Day recess.