African Union leaders are to discuss the idea of a pan-African government, on the second day of their summit.
The Accra summit is the AU's ninth in five years
Libya's Colonel Muammar Gaddafi is championing the idea, but many African leaders in Accra, Ghana, are wary.
Some of the 50 leaders there fear the issue will push the crises in Zimbabwe, Somalia and Darfur off the agenda.
Zimbabwean President Robert Mugabe said unity was vital to make the continent truly independent of the West, as he spoke to a crowd of cheering Ghanaians.
"Unless we put our act together... and start pooling our resources together, we will never, ever prosper from any aid from any source outside Africa," President Mugabe said on Sunday in a speech at the tomb of Ghana's first president.
The idea of a single pan-African government was first promoted by Kwame Nkrumah, who led Ghana to independence in 1957.
The Libyan leader has long been an enthusiastic proponent of the idea.
His proposal at the summit was backed by the Senegalese Foreign Minister, Cheikh Tidiane Gadio.
Mr Gadio said Senegal was prepared to take the first steps towards a pan-African government by joining other states willing to sign such an accord.
"If Senegal wants to build this union with two, three, four more countries, there is not a country in this room that has enough power to tell Senegal you cannot do it," he told the Reuters news agency.
Mr Gaddafi has called for the immediate establishment of a single government, foreign policy and army.
Ghana's President John Kufuor said in his opening speech to the conference that the question of unifying Africa was not in doubt, but the key issue was how to attain it.
"I am confident that at the end of our deliberations, we should be able to arrive at a common understanding on the sort of continental government we want for ourselves, and a roadmap with timelines on its realisation," he said.
African Union Commission head Alpha Oumar Konare told the gathering that Africans needed to "take the bull by the horns and move towards a new country - Africa".
But campaigners on the sidelines of the summit say delivery is the key problem, with leaders already having shown they are unwilling to give up power to regional economic blocs.
"We have regional economy communities that were put in place for West Africa... but nothing is working. From one country to another... there are still a lot of obstacles," a campaigner for the organisation Call To Action Against Poverty told the BBC.
Some leaders believe that by putting so much energy into the unity debate, urgent issues are being neglected.
Nobel Peace Prize winner Desmond Tutu has put his name to a petition calling for the presidents to focus their attention on the conflict in the Sudanese region of Darfur.
The petition says African heads of state have a decision to make - be weak and turn away while innocent people suffer, or be strong and take responsibility for protecting them.
Sudanese President Omar al-Bashir is missing the summit following the death of a close aide in a car crash,
His absence will not help change the minds of those who doubt all the African leaders are willing to work closely together, let alone form a united government, reports the BBC's Will Ross in Accra.
This summit is the ninth since the AU was created five years ago.