“IT’S TIME FOR Gaddafi to go.” So said President Obama — two weeks ago.

Libyan dictator Moammar Gaddafi does not seem to have received the message. His forces are on the counterattack and gaining. Combined with the dispatch of 2,000 Saudi and allied troops into Bahrain to stifle a democratic uprising there, the sense is of a counterrevolution gaining strength across the Middle East. So far the Obama administration has not shown that it has a strategy in response.

Two weeks ago, when Mr. Obama flatly decreed the end of the Gaddafi era — “So let me just be very unambiguous about this,” Mr. Obama said then. “Colonel Gaddafi needs to step down from power and leave” — momentum did seem to be on the side of the rebellion. A modest intervention from supporting countries, such as imposition of a no-fly zone, might have tipped the balance, convincing pilots and higher-ranking officers around Mr. Gaddafi that the future resided elsewhere.

The United States chose not to intervene in that way. It joined with allies in imposing sanctions on Mr. Gaddafi and threatening to bring him before the International Criminal Court. But when it came to a no-fly zone, providing arms to the opposition or other tangible measures, the administration demurred, insisting that the United Nations, NATO and other international groups take the lead. Mr. Obama’s national security adviser, Thomas Donilon, last week said that the United States would insist on backing not only from those traditional allies but from the African Union and the Arab League, too — “not just rhetorical support but actual participation.”

The Arab League subsequently endorsed military action, a breathtaking departure from its traditional opposition to foreign intervention of any kind, and France and Britain have as well. Libyan rebels, who include much of the former government, themselves have begged for help. But the administration remains unconvinced. Secretary of State Hillary Rodham Clinton attended a gathering of European allies that ended without agreement. She held a meeting with the Libyan opposition that concluded without even a public statement. Mr. Obama, repeating his assertion Monday that Mr. Gaddafi must leave, also repeated that “we will be continuing to coordinate closely both through NATO as well as the United Nations and other international fora . . .

Possible interventions include not only a no-fly zone but also providing weapons to the rebels, offering inducements to Gaddafi loyalists to defect, jamming Libyan military radio transmissions or bombing Mr. Gaddafi’s tanks and artillery when they move east. Each option carries risks for the United States, and Mr. Obama’s caution is understandable.

On the other hand, Mr. Gaddafi’s military is weak, and many Libyans clearly are desperate for change. And a Gaddafi victory also carries risks for U.S. interests, as Mr. Obama himself has said. A sacking of Benghazi will be accompanied and followed by a horrific bloodbath. A revitalized dictator is likely to be distinctly unfriendly to Western interests. And other despots will conclude that Mr. Gaddafi’s brand of merciless revenge brings better results than the Tunisian and Egyptian models of accommodating people’s yearning for freedom — and that American threats to the contrary can be discounted.

If Mr. Obama didn’t know it before, by now he has surely seen that the U.S. government does not deliver unless the president insists — and that in turn the “international community” will never act unless the United States leads. An opportunity to help effect historic change may soon close.