MUammar Gaddafi's snipers and tanks are said to be terrorising civilians in the coastal city of Misrata and the US military warned it was "considering all options".
US President Barack Obama said yesterday the US is days away from turning over control of the air assault on Libya to other countries. Just how that will be accomplished remains in dispute.
Mr Obama spoke yesterday with British Prime Minister David Cameron and French President Nicolas Sarkozy in hopes of resolving the squabble.
Gaddafi, meanwhile, made his first public appearance in a week, promising enthusiastic supporters at his residential compound in Tripoli.
"In the short term, we'll beat them, in the long term, we'll beat them. O great Libyan people, you have to live now, this time of glory, this is a time of glory we are living," he said.
Heavy anti-aircraft fire and loud explosions sounded in Tripoli after nightfall, possibly a new attack in the international air campaign. Two explosions were heard in the city before daybreak today.
One of Gaddafi's sons may have been killed, US Secretary of State Hillary Clinton said yesterday.
Ms Clinton also said that people close to Gaddafi are making contact with people abroad to explore options for the future.
She said they were asking, "What do we do? How do we get out of this? What happens next?"
Despite the allies' efforts to keep Gaddafi from overwhelming rebel forces, conditions have deteriorated sharply in the last major city the rebels hold in western Libya.
Residents of Misrata, 200km south-east of Tripoli, say shelling and sniper attacks are unrelenting. A doctor said tanks opened fire on a peaceful protest on Monday.
"The number of dead are too many for our hospital to handle," said the doctor.