IN HIS second inaugural address, President Obama delivered a ringing pledge of U.S. support for American ideals around the world. “We will support democracy from Asia to Africa, from the Americas to the Middle East,” he promised, “because our interests and our conscience compel us to act on behalf of those who long for freedom.”

Just eight months later, the idealism is gone. In what may be the most morally crimped speech by a president in modern times, Mr. Obama explicitly ruled out the promotion of liberty as a core interest of the United States. Instead, he told the U.N. General Assembly on Tuesday, America’s core interests consist of resisting aggression against allies; protecting the free flow of energy; dismantling terrorist networks “that threaten our people” and stopping the development and use of weapons of mass destruction.

No president should cite democracy promotion as the United States’s only core interest or even, invariably, its first priority. A superpower always must juggle competing concerns of security and commerce. But has a president ever boasted that promoting democracy will not be a core interest? To say that America cares more about the flow of oil than the rights of men and women is to diminish the U.S. soldiers and diplomats who have sacrificed to far higher purpose than Mr. Obama would acknowledge. It is to cede the exceptionalism argument to Vladi­mir Putin.

In his speech, Mr. Obama said that America’s core interests are not “our only interests” and that the United States “will continue to promote democracy and human rights and open markets, because we believe these practices achieve peace and prosperity.” Presidents from Franklin D. Roosevelt to John F. Kennedy to Ronald Reagan have promoted these “practices” not just to “achieve peace and prosperity,” as Mr. Obama said, but because they believed deeply that every human being has an inalienable right to live in freedom and dignity and that the United States is uniquely positioned to help other people achieve those rights.

As a practical matter, if a president signals that democracy is not a core interest, if it ranks fifth or lower on his list of priorities, it won’t be promoted at all. Mr. Obama made that clear in his discussion of Egypt’s military government, which, since overthrowing a democratically elected government, has slaughtered hundreds and stifled freedom of the press and association. Mr. Obama noted that “we have not proceeded with the delivery of certain military systems,” but he reassured the generals that the United States will continue working with them on “core interests like the Camp David accords and counterterrorism.” The president insisted that “we will not stop asserting principles that are consistent with our ideals.” But if the generals know that those principles don’t count among U.S. “core interests,” why would they pay any attention to Mr. Obama’s “assertions”?

Mr. Obama may believe that minimizing values in foreign relations is tough-minded and realistic. In fact, it can only diminish U.S. influence, including in matters that he defines as core. “It was not all that long ago that farmers in Venezuela and Indonesia welcomed American doctors to their villages and hung pictures of JFK on their living room walls,” Mr. Obama wrote as a presidential candidate in 2007. “We can be this America again.”

He was right. We could be that America again — but not by cherishing oil over liberty.