CAIRO • Six months after the outbreak of the revolt against his 42 years in power, Moammar Gadhafi's hold on his Tripoli stronghold shows signs of slipping.

Residents of Libya's capital, who for months hesitated to talk openly over the phone, said in calls Friday night that they believed Gadhafi's flight or ouster could be imminent. Three people said the feeling of fear was ebbing.

"It is much quieter today than yesterday and the day before," said one resident, still not willing to reveal his name.

With unexpected swiftness, the ill-trained and ill-equipped rebels from the western mountains this week overtook much of the strategic coastal town of Zawiyah, with its enormous oil refinery, just 30 miles west of Tripoli, the country's capital. By Friday, they had also taken Gharyan, an important outpost along the trade route to the south. Gadhafi troops had concentrated in both towns, and their retreat in the face of the rebels raised new doubts about the loyalist forces' will and cohesion.

As a result of those victories, most of the main roads that had supplied Tripoli have been closed. Many residents, fearing a bloody fight for the capital, are trying to flee.

Residents and officials of the Gadhafi government said the NATO assault on Tripoli reached a new peak this week as bombs rained down on Gadhafi's compound and the palatial home of his intelligence chief and brother-in-law, Abdullah Senussi.

The Libyan leader himself has not made a televised appearance in three months, although Monday he released a low-quality audio recording exhorting Libyans to fight, saying that "the blood of the martyrs is fuel for the battlefield."

Yet some U.S. officials cautioned Friday that the intelligence about what was happening in Tripoli remained murky.

"Clearly, the regime is feeling the pressure, and the opposition is gaining ground each day," said one U.S. official familiar with the intelligence about Libya. But, he said, "How or when that translates into a tipping point or what the endgame might look like is hard to determine."

"At this stage," he added, "Gadhafi might not know what he's going to do from one day to the next."

This is by no means the first time the rebels have seemed to have Gadhafi on the ropes. At the beginning of the uprising, Tripoli and most other cities in the country rose up against Gadhafi, before his militias reasserted control in the west and NATO stepped in to defend the rebel east.

There was fierce fighting Friday in Zawiyah and in Zlitan, a coastal city east of Tripoli, an indication that at least some elements of the well-equipped Gadhafi forces remained determined to carry on the fight. Driven out by a NATO attack overnight, the loyalists returned to Zawiyah with renewed force, lobbing mortar rounds and rockets and retaking buildings around central Martyrs Square.

By the end of the day, however, rebel fighters were pouring in from other cities to counter the Gadhafi forces, and a reporter for Al Jazeera in Zlitan said the rebels had prevailed there.

As the fighting draws closer to Tripoli, residents are feeling the pressure. For the first time, they say, they cannot easily leave the city. Hundreds of them have clogged narrow back roads as they try to flee to the relative safety of the rebel-held mountains to the south.

Officials of the Gadhafi government continued to insist that he would fight to the end. A senior Foreign Ministry official, in a conversation in which he was granted anonymity to speak about internal deliberations, said weeks ago that Gadhafi supporters would not give up even if they ran out of trucks and fuel.

"We will ride camels," he said.

Musa Ibrahim, the government spokesman and a member of Gadhafi's tribe, continued to insist through the state-run news media that the government would weather the current "crisis."

And Fouad Zlitni, Gadhafi's personal translator and a Libyan diplomat, argued in a telephone interview from Tripoli that the rebels did not deserve credit for their gains in Zawiyah because it was NATO bombs that made their advance possible.

"They should say NATO took them to Zawiyah," he said. "What is happening in Libya is the law of the jungle."