Ugandan President Yoweri Museveni has said Somalia's transitional government should be given another year to consolidate gains against militants.
Otherwise, Uganda will withdraw its troops helping the government fight Islamist al-Shabab militants, he said.
The current mandate for the UN-backed government is due to expire on 20 August and the UN is calling for elections to be held quickly.
Mr Museveni said polls this year would allow the militants to reorganise.
Uganda currently contributes about 5,000 troops to an African Union (AU) peacekeeping force, called Amisom, in Somalia. Burundi supplies the rest of the force.
"It seems to us that the win-win situation for all parties seems to be an extension of the Transitional Federal Institutions for a period not exceeding one year," Mr Museveni told an international meeting on Somalia held in Uganda's capital, Kampala.
Elections held too soon, he warned, would "allow the extremists time to reorganise and cause problems and undermine the battlefield gains so far obtained".
He added: "If the current system collapses, or if it is seriously undermined, we can have no justification to stay in that situation - we will leave Somalia."
Somali President Sharif Sheikh Ahmad told the International Contact Group on Somalia that the country was too unstable for a vote. He also called for the transitional government's tenure to be extended.
The AU force in Somalia deployed to Mogadishu in 2007 to back the weak interim government.
Somalia has been racked by constant war for more than 20 years. Its last functioning national government was toppled in 1991.
