Media reports from Somalia say an alliance of warlords is trying to regroup north of Mogadishu after losing control of the capital to Islamic militias on Monday.
Witnesses say the warlords are preparing defensive positions around their last stronghold, the town of Jowhar. Islamic militias are said to be south of the town, awaiting orders to attack.
The militias, loyal to Sharia courts, have been fighting since February with a warlord coalition widely believed to have covert U.S. backing.
U.S. officials have refused to either confirm or deny the allegation.
More than 350 people have died in the fighting, many of them civilians caught in the crossfire.
President Bush has said he is watching events in Somalia closely, and is concerned the eastern African nation could turn into a safe haven for al-Qaida terrorists.
The Islamic leaders have said they are trying to restore order to Somalia, which has not had an effective central government since 1991.
Some information for this report was provided by AFP, AP and Reuters.