Jacob Zuma took power Saturday in the culmination of an extraordinary political comeback, pledging to Nelson Mandela and the nation to renew the spirit of commitment and hope of South Africa's first black presidency.

Zuma was once imprisoned under apartheid and spent years in exile before surviving corruption and sex scandals and a party power struggle to reach the nation's highest office. He has been embraced by many South Africans with a fervor usually reserved for Mandela.

The elder statesman was cheered as he arrived for the inauguration in a golf cart to join the 5,000 VIP guests and tens of thousands of ordinary South Africans who had gathered for the ceremony.

In a speech after taking the oath, Zuma looked back to 1994, when Mandela became president after leading the campaign that defeated apartheid.

"We gather here determined to renew that most solemn undertaking, to build a society in which all people are freed from the shackles of discrimination, exploitation, want and disease," Zuma said.

He now leads Africa's economic powerhouse, but it is a country where at least a quarter of the work force is unemployed and 1,000 people die of AIDS every day.

Zuma promises to speed up delivery of houses, clinics, schools, running water and electricity. But he also has acknowledged the difficulties amid a global economic meltdown. According to government figures, 208,000 jobs were lost between the last quarter of 2008 and the first quarter of 2009.

"Jobs are being lost in every economy across the world. We will not be spared the negative impact, and are beginning to feel the pinch," Zuma said Saturday. "However, the foundations of our economy are strong and we will need to continue to build on them."

He said his government "shall not rest and we dare not falter" as long as South Africans were dying of preventable disease, struggling to feed their families or get an education, enduring without clean water or decent shelter.

Moses Gama, a 30-year-old unemployed social worker who was in the crowd on the lawn, said the speech reassured him that Zuma had heard South Africans' concerns, but also made him aware of the challenges and the need for both patience and action.

"Our president, Jacob Zuma, he always goes straight to the point," Gama said.

Phila Xaba, a priest who watched the live national TV broadcast of the ceremony from Soweto, said the ANC had achieved a lot in the last 15 years, "but still a lot needs to be done to improve education, reduce unemployment and fight crime." He said he was convinced Zuma can deliver.

After the formal part of the program held on the stone verandah of a colonial-era complex, Zuma left the dignitaries in their chic furs or designer traditional outfits. He thanked the crowd gathered on the lawn wearing jeans and ANC T-shirts who had watched the inauguration on TV screens. In a brief speech, most of it in Zulu, he said their embrace of democracy was inspiring.

Zuma, a 67-year-old former guerrilla fighter and intelligence chief of the African National Congress, led his ANC party to an overwhelming parliamentary victory in April. Parliament elected him president on Wednesday.

The ANC, though, did not win the two-thirds majority it did in 2004, a slide largely attributed to a split in the party because of Zuma's power struggle with ANC colleague and former President Thabo Mbeki. The crowd on the lawns Saturday repeatedly booed Mbeki, but their jeers were out of the hearing of the VIPs.

Many impoverished black South Africans believe Zuma's personal battles and eventual triumph give him special insight into their own struggles and aspirations.

Zuma once herded livestock in the rural Zulu heartland. His father was a policeman who died when Zuma was a boy. His mother worked as a maid in the coastal city of Durban. Zuma was denied a formal education and by 15 he was doing odd jobs to help support his family.

He joined the ANC in 1959 and by 21 he was arrested while trying to leave the country illegally. Zuma was jailed for 10 years on Robben Island, alongside Mandela and other heroes of the anti-apartheid struggle. It was there that he continued with his schooling and began making a name for himself among ANC prisoners.

After prison he married Sizakele Khumalo, his childhood sweetheart from his Zulu village — the first of several marriages. Zuma's unabashed polygamy has raised questions about which of his three current wives would be first lady. On Saturday, all three were reported present but only Khumalo accompanied him to the stage, where Zuma dropped down onto his knees before Mandela in a traditional sign of respect.

Zuma left South Africa in 1975 for 15 years of exile spent in neighboring Swaziland, Mozambique and Zambia where he was appointed chief of the ANC's intelligence department. Following the lifting of the ANC ban in 1990, Zuma was one of the first leaders to return to South Africa.

He was appointed deputy president in 1999 by Mbeki who fired him in 2005, when Zuma was implicated in the corruption trial of a close friend and financial adviser.

Mbeki later lost the party leadership to Zuma and was forced last year to yield the presidency to an interim successor, Kgalema Motlanthe.

Prosecutors lifted the last obstacle in Zuma's path last month when they announced that they were dropping corruption charges against him, saying the case had been manipulated for political reasons and the criminal charges would never be revived.

Sydney Mokoena, a 48-year-old Pretoria high school teacher, said he admired Zuma for the calm he showed during his corruption battles and a 2006 rape trial that ended with acquittal. Mokoena had roused his 10-year-old daughter, Thula, at 4:30 a.m. to get to the lawns early.

Zuma will be "a dynamic and vibrant president," Mokoena said. "That's what South Africa needs. He's down to earth and he'll listen."

Mokoena laughed when Thula said she hoped for a glimpse of Mandela.

"We can have three or four or five presidents," Mokoena said, "people will still be talking about Mandela."