Victory prayer at Obama's ancestral home

Kenyans in Barack Obama's ancestral homeland prayed for victory on Tuesday as he aimed to become the first African-American president of the United States.

The western town of Kisumu, on the shores of Lake Victoria, was in a frenzy of excitement as the country's favourite adopted son began the last leg of his race for the White House.

The Democratic candidate's late father hailed from the rural region, and exuberant Kenyans gave his Republican war hero rival John McCain little hope of making a comeback after lagging for weeks in the opinion polls.

"I don't think McCain would have sold anything," said Kwamboka Okari, a woman selling Obama buttons in Kisumu's hot equatorial sun. "I don't see how McCain would come here."

Police have tightened security as family, friends, well-wishers and hordes of local and foreign journalists descend on Kogelo, the tiny village about an hour northwest of Kisumu, where Obama's 87-year-old grandmother lives.

Mass prayers for his victory were planned there on Tuesday, and if he wins, his family plans to roast a bull in celebration.

Since 2004 when Obama was running for the Senate in Illinois, the Harvard-trained lawyer and civil rights activist has enjoyed rock star status in the east African nation.

Born in Hawaii to a white mother from Kansas and a Kenyan father, he is idolised by many the way the Irish saw US President John F. Kennedy in the 1960s as one of their own who succeeded beyond their wildest dreams.

US election fever has swept Kenya as the Democratic hopeful nears the world's most powerful position.

Babies have been named after him, people have drunk "Senator" beer in his honour, pop stars sing his praises and "Obama: The Musical" opened in the capital Nairobi on Sunday.

"Obama-mania! Obama-mania!" one Kisumu shoe-shiner shouted at passing customers in the busy town centre.

Many Africans hope his victory would mean more U.S. support for local development projects and an improvement in living conditions for the majority on the world's poorest continent.

But analysts have warned that Obama will be able to do little to bring tangible benefits to Africa, and that he does not have a strong track record of interest in the continent.

"My brother may not directly influence the development in the village," half-brother Abongo Malik Obama said.

"But there are things that he stands for, and it is the people who believe in those things who will make moves to improve living standards," he told reporters in Kogelo.

Obama announced on Monday that his maternal grandmother had died from cancer.