The appeal had the ring of a last gasp.

France’s foreign minister, Alain Juppe, said Wednesday that there was still time for military intervention to turn the tide against embattled leader Moammar Gaddafi in Libya. All the United States and other major powers had to do, he suggested, was follow France’s lead to pass a quick Security Council resolution and then send warplanes to neutralize Gaddafi’s air force.

“This is urgent,” Juppe declared on his blog, adding: “We have often seen in our contemporary history that the weakness of democracies leaves the field open to dictatorships. It is not too late to defy this rule.”

Juppe’s clarion call was the latest entry in an unusual and unclear diplomatic initiative by President Nicolas Sarkozy’s government. Even as Gaddafi’s military closed in on rebel forces retreating to their last major redoubt in Benghazi, Libya’s second-largest city, the French campaign continued at the United Nations with a proposed council resolution for military action by outside powers.

“The president of the republic and the British prime minister have just solemnly called on council members to examine it and adopt it,” Juppe wrote, adding that “several Arab countries” have said they would also take part in whatever military action is decided.

The chief Foreign Ministry spokesman, Bernard Valero, said the revised text now before the Security Council is probably the last real chance for the international community to act decisively in Libya. “It is now up to everyone to assume his responsibilities,” he added.

France’s proposal, at first presented as a suggestion for establishing a no-fly zone over Libya and then broadened to include selective airstrikes, was brought forward in conjunction with Britain. It was raised at the United Nations two weeks ago, then at a NATO defense ministers meeting last week in Brussels, then at a European Union summit and finally at a Group of Eight foreign ministers meeting Monday and Tuesday in Paris.

But in all the forums, it was met with tepid U.S. and Russian responses and opposition from Germany, in effect sinking the idea. Unsaid but clear in the mind of specialists was that almost any kind of military intervention would be possible only with extensive cooperation from the United States, the only power able to field sufficient aircraft carriers, intelligence, command and control equipment and warplanes on short notice.

Washington, however, has so far been unwilling to engage on such a proposal. President Obama has declared that Gaddafi must step down as Libyan leader but deferred to allies on the means for making that happen, meaning he was not eager to have U.S. forces intervene in an Arab civil war. In the meantime, Gaddafi’s military has seized the initiative on the battlefield

Part of the problem also was lack of clarity.

The Franco-British initiative was first described as imposition of a no-fly zone so Gaddafi could not use his air force against the rebel forces. But Sarkozy said during the E.U. summit in Brussels that he had in mind bombing Libyan runways and warplanes rather than a no-fly zone. The bombing would occur only if the Libyan air force was used for massive attacks against unarmed civilians, he added, and would have to have a legal basis such as a Security Council resolution.

Juppe, however, made it clear in comments after the G-8 meetings here and in his blog Wednesday that he viewed the proposed bombings as a way to blunt Gaddafi’s offensive against the rebel leadership in Benghazi. Gone was the precaution underlined by Sarkozy that such action would be contemplated only in case of massive civilian casualties.

“Only the threat of use of force can stop Gaddafi,” he said. “The Libyan dictator has upset the battlefield balance by bombing his opponents’ positions with the several dozen airplanes and helicopters at his disposal. We can neutralize his air capacities by targeted strikes. That is what France and Britain have been proposing for two weeks.”

The difference in emphasis between Sarkozy and Juppe means little, Valero said, because there is no distinction between protecting civilian populations and protecting the ragtag rebel forces, most of whom are civilians. In either case, military action by the West would affect the outcome of the conflict, he explained.

The aggressive French campaign, critics here said, in part reflected Sarkozy’s embarrassment over his government’s slow response to the earlier revolts in Tunisia and Egypt. The dictators in both nations — Zine el-Abidine Ben Ali in Tunis and Hosni Mubarak in Cairo — were close allies; Paris endorsed their overthrow by popular uprisings only when it became clear they could no long hold out.

In Libya’s case, however, France has been in the lead in demanding that Gaddafi step down. It became the first country to recognize the rebel leadership as the legitimate representative of the Libyan people and remains the only one to have done so.

For being out front so clearly, Sarkozy was condemned Wednesday by Gaddafi’s most influential son, Saif al-Islam Gaddafi, who called the French leader “crazy” in a television interview and tried to embarrass him by saying the Libyan government financed his election campaign in 2007.

Sarkozy’s office issued a swift denial. But the accusation was likely to become part of the political debate in France as the country moves closer to the next presidential vote, scheduled for spring 2012.