Umaru Yar'Adua is the man most likely to become the president of Africa's most populous and oil-rich country, Nigeria. But until he emerged as the ruling party candidate in next month's presidential polls, few people paid him much attention. Sarah Simpson has more in this VOA report from his home town of Katsina.

Until Umaru Yar'Adua emerged as the ruling party candidate in crucial April elections, few had paid much attention to this governor from one of Nigeria's most northerly and remote states.

Described as unassuming and soft-spoken, he moves around his home city without any of the flashing lights and security cavalcades that accompany other state governors.

In a sitting room of the modest family home, his sister, Habiba, recalls that her brother has never sought special attention, even as a young man working on the family farm.

"Our late brother asked him to go to the farms, because, by that time, the farm was almost spoiled, he said. "And, he stayed there, and he worked, and that was where I saw his sincerity and honesty. He worked as the manager of the farm, but still he used to work with the laborers as if he was not the general manager."

Nigeria is known for corruption and grinding poverty amid the burning gas flares of a multi-billion-dollar oil industry. Since the end of military rule in 1999, religious and ethnic violence has soared, killing thousands.

Outgoing President Olusegun Obasanjo is a former military ruler, who was elected to office eight years ago.

He has spent his last few weeks in office whipping up support at political rallies for his chosen successor.

Critics of Yar'Adua say that he does not have the strength of character to dominate an unruly nation like Nigeria, and that he was chosen to enable the outgoing president to retain the reigns of power after his own departure.

Chief among the critics is Vice President , who is currently battling in court to get his name back on the presidential ballot as a candidate, here speaking at a recent press conference.

"It is your right to freely choose your leaders, but this time you must be careful of which leaders you choose. Nobody can take that away from you," said Abubakar.  "Nobody should foist a leader on you, nobody should foist a leader on you, particularly somebody you do not know and who does not know you."

Abubakar accuses President Obasanjo of using the Nigerian courts and electoral commission to block his candidacy after the two had a very public fall out.

Abubakar is no longer a member of the ruling People's Democratic Party.

Backed by the money and machinery of government, analysts say, PDP candidate Yar'Adua has the strongest chance of winning this month's polls.

A billboard bearing Umaru Yar'Adua's face looks down on a street vendor in Katsina, Nigeria, 19 Mar 2007

His father was a minister in Nigeria's first post-independence government. His older brother, Shehu, was a soldier and leading force in the coup that put Mr. Obasanjo in power in the 1970s, and worked as Mr. Obasanjo's right-hand man throughout his time as military ruler.

While his older brother worked alongside Mr. Obasanjo, Yar'Adua was a chemistry teacher at his local polytechnic.

But he has long been active in politics, and for the last eight years, he has been governor of Katsina State, where he has adopted Islamic Sharia Law. In total, 12 northern Nigerian states have adopted Sharia since 1999.

Nigeria is evenly split between Muslims and Christians, and there is periodic violence between the two groups.

Yar'Adua assured Anglican Archbishop Peter Akinola in a special meeting last month that he would respect all religions should he be sworn in as president on May 29.

Dressed in the flowing robes and matching cap favored in northern Nigeria, Yar'Adua told reporters in the federal capital, Abuja, recently that affirming the rule of law would be one of his priorities, should he become president.

"I would like to see that I have a government that is trusted and credible and that can be so, if we have proper respect for law and order - in other words the rule of law is placed in an exulted position."

Yar'Adua had to abandon campaigning for several days last month when he was flown to Germany for medical treatment relating to a long-standing kidney problem. Party insiders said it was a routine check-up.

Opponents pounced on it as another sign of weakness in a man seeking to take on one of the most challenging jobs in African politics.

Yar'Adua has repeatedly praised President Obasanjo's rule since he was elected.

"After eight years, clearly the country has stabilized relative to the situation in 1998, and there is a clear improvement in the living conditions of our people. Democracy really has made possible access to wealth for the greater majority of the population."

But poverty remains pervasive. Despite exporting billions of dollars of oil every year, 70 percent of Nigerians exist on less than $2 a day, according to the United Nations.

Unrest in the oil producing region of the Niger Delta has escalated, with more than 100 foreign oil workers taken hostage by gunmen in the last 12 months. There, militant groups say they are fighting for a greater share of the oil wealth to develop their region, where many live without access to electricity or clean drinking water.

Presidential elections are due to take place on April 21, and the new president will be sworn in before June.