By Jon Schuppe
A month before Nigeria's national elections, retired Gen. Muhammadu Buhari traveled to London for a speech in which he described his vision for the troubled republic, torn by a war with Boko Haram terrorists and sapped by plunging oil prices.
Buhari, the 72-year-old head of the opposition All Progressives Congress who briefly led the country following a 1983 military coup, promised to "choke" Boko Haram, implement economic reforms and root out waste and corruption.
"Let me assure you that if I am elected president, the world will have no cause to worry about Nigeria as it has had to recently; that Nigeria will return to its stabilizing role in West Africa," he told an audience at Chatham House, an international policy institute.
Now, with this week's resounding win over Goodluck Jonathan, Buhari has to prove he can deliver.
He is taking over Africa's largest economy and one of its most turbulent democracies, a country that has never before handed power to an opposition party without force. Nigeria sees itself as the one country to lead Africa into the future.
"With 183 million people — more than Russian Federation — what happens in Nigeria has an impact on the entire African continent," said John Campbell, a former U.S. ambassador to Nigeria.
The largely peaceful election alone is enough to raise Nigeria's prestige and influence, Campbell said.
But the country has profound problems.
Boko Haram's Islamist militants have killed thousands in the country's north in an attempt to create a regional caliphate. A February offensive drove the group back, but it remains a potent threat.
A steep decline in global oil prices has devastated Nigeria's economy, which derives about 70 percent of its revenue from oil. About a third of Nigerians live in poverty, Buhari has pointed out.
The country is split among ethnic, religious and regional lines, divisions that Buhari will have to transcend. Buhari is a northern Muslim; his predecessor, Jonathan, represented southern Christians.
Because he is Muslim, Buhari has had to defend himself against accusations he'd impose hard line Islamic law — and analysts say the allegations are not realistic.
Historically, power and oil revenues have been divvied up by Nigerian elites. That has led to extraordinary corruption, which Buhari has promised to eliminate.
Campbell said there are reasons to believe Buhari can be highly effective. That impression is rooted in his relatively modest lifestyle, notable in a country where former government "big men" leaders live lavishly. Campbell said that when he was ambassador from 2004 to 2007, he visited Buhari at his home, where he answered the door himself and didn't appear to have any servants.
"He's probably the only Nigerian politician or political figure who is genuinely popular on the street in the north," said Campbell, who is now a senior fellow at the Council on Foreign Relations.
This will be Buhari's second crack at leading Nigeria. The first one ended disastrously.
He seized power in a 1983 military coup d'etat. While in office, he engineered a legendary crackdown on government corruption, but was also criticized for trampling civil rights. After 18 months, he was ousted in another coup.
Since then, Buhari — whose human-rights record has been fiercely criticized — has described himself as a convert to democracy. He ran for president three times before before this week's victory.
The United States has had chilly relations with Nigeria, mostly due what has been seen as an ineffectual response to Boko Haram, which kidnapped more than 200 schoolgirls last April. Buhari's election was endorsed by the United States Tuesday.
A U.S. official saying the new president was in a position to build a "new" Nigeria that could lead Africa into a new era of modernization and peaceful democratic change.
The Associated Press and Reuters contributed to this report.
Jon Schuppe is a writer on the enterprise unit at NBC News. He arrived in April 2014, after two years...