New U.S. intelligence assessments conclude that government forces, already beset with morale problems and a steady stream of defections, are now hard-pressed to find fuel for military vehicles after rebel troops shut down a key pipeline. If current trends continue, loyalists troops will run out of fuel by summer’s end, and the Gaddafi government will face a worsening cash and credit shortage because of international sanctions, the reports say.

While the momentum has generally favored the rebels for weeks, Western analysts are seeing troubles escalate on the loyalist side, possibly explaining the surge of interest in finding a negotiated end to the fighting, according to two senior U.S. officials who have seen the assessments.

“There has been a shift,” said one of the officials, who insisted on anonymity in discussing the classified reports. “The situation is looking much better [for the rebels] than it was just a month ago.”

This official, who said he had been generally pessimistic about rebel prospects since the start of the fighting in February, said he was “starting to be slightly optimistic” about the chances for either a political solution or a complete collapse of the Gaddafi government in the coming weeks.

A senior European diplomat echoed the U.S. view and said there were multiple signs — including intercepted communications between Libyan officials — that Gaddafi insiders were looking for an exit.

“It’s not just the signals they’re sending publicly, but also what we know through other means about their state of mind,” said the diplomat, who also requested anonymity in discussing his government’s internal assessments. “In the last couple of weeks it appears that [Gaddafi] is less willing to do whatever it takes to stay in power.”

The overtures by Gaddafi aides were described publicly by French Foreign Minister Alain Juppe, who said in a French radio interview that the regime was “sending messengers everywhere — to Turkey, to New York, to Paris” — to explore ways to end the conflict.

“We are receiving emissaries who are telling us: ‘Gaddafi is prepared to leave. Let’s discuss it,’ ” a Reuters news report quoted Juppe as saying. Juppe described the outreach as “contacts” but not formal negotiations.

In Washington, the State Department confirmed that the Obama administration had received similar messages. But spokeswoman Victoria Nuland added that Gaddafi had not yet met the conditions to bring the conflict to an end.

“We are seeing the same thing that some of our Western partners are seeing,” Nuland told reporters Tuesday. “But unless and until we are sure that the conditions of [U.N. Security Council Resolution] 1973 can be met, and that he understands that it’s time for him to step down, we don’t have a solution.” She referred to a U.S.-backed measure calling on Gaddafi to halt attacks on civilians and withdraw his forces to their barracks.

Gaddafi has frequently expressed a willingness to negotiate with the rebels who have battled his government since February. But until now he had insisted on remaining in Libya and participating in the talks on his country’s future. But in a further sign of new flexibility, Prime Minister Baghdadi al-Mahmoudi said this week that Gaddafi was no longer insisting on a role.

“We are willing to negotiate unconditionally,” Mahmoudi said in an interview published Tuesday in the French newspaper Le Figaro. But he added that a cease-fire should be declared as a prerequisite for negotiations.Mahmoudi acknowledged that much of his government’s military capability had been destroyed by NATO warplanes, and he said the flow of money, petroleum and supplies had been badly disrupted by months of fighting.

The apparent diplomatic movement comes amid signs of weariness on both sides of the conflict. While anti-Gaddafi forces continue to gain ground in the mountains west and south of Tripoli, the battle lines in the east have remained essentially frozen for weeks. It is far from clear that the ill-equipped rebel army is prepared to challenge Gaddafi’s elite troops in the capital, although opposition leaders claim that sympathizers in Tripoli will rise to help them when the time comes.

Two top rebel commanders of large militias in the mountains west of Tripoli said in interviews Tuesday that Gaddafi forces are showing signs of low morale. They say the government troops are kept in barracks and are then bused to fronts, and are not allowed leave or to carry their weapons until they are sent to fight.

The rebel commanders, one a defector himself, reported ongoing defections, including from within the top ranks of the government military. They said officers who defected have had their houses vandalized or burned in Tripoli and their families harassed and removed from government jobs and payrolls.

A Libyan air force general, who said he defected a week ago and declined to give his name, said that the officer corps of the Libyan government military is hollowing out and that Gaddafi is relying increasingly on irregular foreign troops and his security services.

U.S. intelligence assessments project a variety of possible outcomes, ranging from an internal collapse of Gaddafi’s government to a negotiated settlement or even an outright military win by the rebels. But while the picture appears to be brightening, the final resolution could still be weeks away, said the U.S. official briefed on the reports.

“No one is saying that a victory is imminent,” the official said.

*Correspondent William Booth in Zintan, Libya, and staff researcher Julie Tate contributed to this report