WASHINGTON, Nov. 20 — An array of religious, civil rights and political leaders are appealing to President Clinton to declare a moratorium on federal executions in the closing days of his presidency.

A letter delivered to the White House today and signed by 40 people, including the former White House counsel Lloyd N. Cutler and several other onetime members of the Clinton administration, urged the president to “prevent an unconscionable act — executing individuals while the government is still determining whether gross unfairness has led to their death sentences.”

Asked about the initiative, White House officials said Mr. Clinton had indicated no inclination to declare a moratorium.

Organizers sought signers who they thought would have influence with the president. The signers included the Nobel laureate and Holocaust historian Elie Wiesel, the financier and philanthropist George Soros, members of the committee established by Mr. Clinton to study race relations in America and three Roman Catholic bishops.

In a separate letter calling for a moratorium, former President Jimmy Carter and his wife, Rosalyn, told Mr. Clinton that a federal execution “would diminish the United States’ moral authority abroad.” The letter, sent by the Carters last month, is to be released at a news conference that the organizers have scheduled for Tuesday.

The activity precedes by three weeks the scheduled execution on Dec. 12 of Juan Raul Garza, sentenced to death for three drug-related murders. Mr. Garza is one of 21 federal prisoners on death row. His would be the first federal execution since 1963.

Mr. Garza was earlier scheduled to be executed on Aug. 5. But Mr. Clinton granted a reprieve because of concerns about racial and geographic disparities in the application of the federal death penalty, along with what was then an absence of federal clemency procedures.

Then, in September, a Justice Department survey concluded that in 75 percent of the cases in which a federal prosecutor had sought the death penalty, the defendant was a member of a minority group, and in more than half the cases, an African- American.

In addition, the survey found that a handful of United States attorneys accounted for about 40 percent of the death penalty cases. Attorney General Janet Reno said at the time that she was “sorely troubled” by the findings, and ordered further study.

The letter sent to the president today called for a moratorium until the study was completed and there had been a period of public debate. This would surely carry any moratorium into the next administration.

Other signers of the letter include Mary Francis Berry, chairwoman of the United States Commission on Civil Rights; Julian Bond, chairman of the N.A.A.C.P.; Kerry Kennedy Cuomo, founder of the R.F.K. Center for Human Rights; Bishop Joseph A. Fiorenza of Galveston-Houston, president of the National Conference of Catholic Bishops; John Hope Franklin, chairman of the President’s Initiative on Race; the Rev. Theodore M. Hesburgh, former president of the University of Notre Dame; Fred Korematsu, Japanese- American civil rights leader; Anthony T. Kronman, dean of the Yale Law School; Mario Obledo, president of the National Coalition of Hispanic Organizations; and Robert B. Reich, former secretary of labor.