A bipartisan chorus of political and legal voices is calling on the Obama administration to release a declassified version of the Justice Department memo that provided the legal analysis sanctioning the killing in Yemen last week of Anwar al-Awlaki, a U.S. citizen.

They said that the reasoning behind the extraordinary step of killing an American cannot be kept secret from scrutiny if the public is to continue to support counterterrorism operations. Awlaki was killed in a CIA drone strike.

“While U.S. counterterrorism operations are, by necessity, classified, I do believe the administration should make public its legal analysis on its counterterrorism authorities, whether in the form of a legal opinion or a white paper,” said Sen. Dianne Feinstein (D-Calif.), chairman of the Senate Select Committee on Intelligence. “For both transparency and to maintain public support of secret operations, it is important to explain the general framework for counterterrorism actions.”

Sen. Carl Levin (D-Mich.), chairman of the Senate Armed Services Committee, also said this week, “I would urge them to release the memo. I don’t see any reason why they shouldn’t.”

The White House did not respond to a request for comment. A Justice Department spokeswoman declined to comment.

Both Feinstein and Levin said they supported the lethal action.

Awlaki was born in New Mexico, and administration officials said he was the chief of “external operations” for al-Qaeda’s affiliate in Yemen, which has attempted a number of terrorist attacks on the United States.

Several former George W. Bush administration officials also said that some version of the legal opinion, written in 2010 by the Justice Department’s Office of Legal Counsel after consultations across the executive branch, should be released to make a public case that the killing of Awlaki was legal under U.S. and international law.

“I do think it would be important for domestic audiences and international audiences for the administration to explain how the targeting and killing of an American complies with applicable constitutional standards,” said John B. Bellinger III, former legal adviser to the State Department in the Bush administration.

Senior Obama administration officials — including John O. Brennan, the president’s counterterrorism adviser, and Harold Koh, the State Department legal adviser — have given speeches that offered a broad rationale for U.S. drone attacks on individuals in al-Qaeda and associated forces.

They argued that deadly force is legal under the 2001 congressional authorization of the use of military force and that the United States, acting in self-defense, is not limited to traditional battlefields in pursuit of terrorists who present an imminent threat.

But Jack Goldsmith, a Harvard law professor who headed the Office of Legal Counsel in the Bush administration, argued on the Lawfare blog that “there has been practically nothing said officially . . . about the executive branch processes that lie behind a strike on a U.S. citizen, or about what constitutional rights the U.S. citizen target possesses, or about the limitations and conditions on the president’s power to target and kill a U.S. citizen.”

Bellinger said he believes that the legal analysis can be extracted from the opinion without revealing other classified information.

Some advocates said the government’s position of not acknowledging the CIA’s drone program because of its classified status has become a sham because administration officials trumpet it in news leaks and seek credit for its success in devastating al-Qaeda.

“I think there is growing unease across the political spectrum with the government boasting to the media in leaks about the drone program and then going into court and saying, sorry, that’s classified,” said Ben Wizner, a lawyer with the American Civil Liberties Union.

Since last year, the ACLU has been seeking, under the Freedom of Information Act, records from the Office of Legal Counsel “pertaining to the use of unmanned aerial vehicles by the CIA and the armed forces for the purpose of killing targeted individuals.”

The government, in its July response, said the “OLC can neither confirm nor deny the existence of any responsive documents related to alleged CIA operations.”