After a year of trying, the Bush administration still has not produced a candidate to head the National Institutes of Health. Its latest effort broke down when, after three rounds of negotiations, William H. Danforth, chancellor of Washington University in St. Louis, withdrew from consideration.

According to White House officials, Danforth withdrew last month after the administration said government ethics rules would require that he disassociate himself from a large charitable family trust that he administers. He, like his brother, Sen. John C. Danforth (R-Mo.), is an heir to the Ralston-Purina fortune.

A senior White House official, recounting the NIH saga, said that William Danforth had been in negotiations for the job three times in the past year, withdrawing once in a burst of publicity when the administration tried to apply "litmus tests" of Danforth's position on abortion and fetal tissue research. A second round resulted in Danforth saying no because of personal reasons, and last month he withdrew when the White House said it was unable to waive the ethics rule.

One official said the White House is awaiting a new recommendation from Health and Human Services Secretary Louis W. Sullivan, but that the secretary "did not have to go back to square one, since he was looking at other candidates all along." A new candidate is not expected before Congress returns next month.