National Cancer Institute Director Andrew von Eschenbach will focus solely on his position as Food and Drug Administration commissioner.

Critics had said Von Eschenbach could not perform both jobs well, and that he could face a conflict of interest when dealing with NCI matters before the FDA.

"I am now devoting my energies to the work of FDA in protecting and advancing the health of the American people, " Von Eschenbach said in an e-mail to staff.

Von Eschenbach will no longer participate in, "other matters involving NCI as a party in which FDA is exercising its regulatory authority."

Sen. Edward Kennedy said the change "does not go far enough" to alleviate concerns that both agencies need permanent, full-time leaders.