``The individual selected could be charged with leadership of American government efforts to promote resolution of the underlying problems responsible for the continuing conflict in Darfur,'' InterAction said in a letter to Bush dated Thursday.
The previous envoy to Sudan, former Sen. John Danforth, was appointed in 2001 to work on the peace process that resulted in a peace agreement in the north-south conflict.

Danforth resigned in December from his post of U.S. ambassador to the United Nations.

Darfur, in western Sudan, has been in conflict for more than two years, with rebel groups fighting the government for more power and resources. Khartoum responded by arming militia, which have been accused of raping and killing.

``We appreciate the leading role the U.S. government has played in providing life-saving relief to the two million affected Sudanese,'' the letter said.

``However, efforts to bring peace to the region appear stalled,'' it said. ``If those displaced remain too afraid to return home within the next several months they will be unable to plant crops. The consequent absence of a harvest will require that they continue to receive international aid for at least another year.''

Members of the group, which says it is the largest alliance of relief and development nongovernmental organizations working overseas, met with White House national security adviser Stephen Hadley on Thursday and discussed Sudan.

A senior administration official, on condition of anonymity, said no decision has been made to appoint a new envoy for Sudan to replace Danforth. He noted Secretary of State Condoleezza Rice and other officials placed a high emphasis on Sudan.