Obama, who continues to be one of President Robert Mugabe’s staunchest critics, was personally replying to selected questions from readers of The Star as part of a joint initiative with the US embassy.

On his country’s rich melting pot of cultures and religions, he noted that American citizens had roots in various regions of the world and that the future of American politics would reflect that diversity.

‘I believe our best days have yet to come’

"I believe our best days have yet to come."

Several questions posed by readers were about Zimbabwe.

The US president said he was deeply concerned about Zimbabwe’s people, "who have suffered for far too long".

Direct assistance to Zimbabweans, including hundreds of millions of dollars in food aid, would continue.

While these measures could provide some relief, development depended ultimately on good governance that served the needs of the people.

"That was the ingredient which has been missing under President Mugabe," Obama said.

He had pledged $73-million (R565m) in additional support for Zimbabwe’s people after meeting Prime Minister Morgan Tsvangirai in June, and the US would continue to explore ways to help further "without empowering the forces of repression".

Asked what he thought of African leaders who wanted to change their country’s constitution to remain president for longer, Obama echoed what he had told the Ghanaian parliament in July: "Africa doesn’t need strongmen; it needs strong institutions."

Third-term bids that involved tampering with the constitution or worse "were steps in the wrong direction".

"Citizens have a responsibility to resist these efforts, regional leaders have a responsibility to speak out against them, and friends of Africa, like the United States, have a responsibility to discourage them as well."

Asked by pupils from St Peter’s College in Joburg whether he believed America was ready for a Hispanic or Asian president, he said "absolutely".

On what he had hoped to become while growing up, Obama said: "I hoped to make a difference."