Yemi Osinbajo has played an increasingly prominent role in Nigeria's government since he was appointed as President Muhammadu Buhari's deputy in 2015.
Nowhere has that been more clearly demonstrated than at a recent question-and-answer session on the current campaign trail, when the lawyer and church pastor spoke more than his boss.
When the 76-year-old Buhari did speak, his critics accused him of being too old, ill or out of touch to grasp the issues at stake.
But he found a loyal ally in his vice-president. "He (Buhari) is not an orator," Mr Osinbajo stated afterwards. "My business is oratory. I'm a lawyer. The reason why you have a person like that is integrity."
President Buhari has publicly shown his appreciation for his colleague, calling him his "running mate turned partner in service ... and friend".
To some extent, Mr Buhari and Mr Osinbajo are a political odd couple.
In one campaign poster for the 2015 election, the President was dressed in a black dinner suit, white shirt and velvet bow tie and loomed uncomfortably over his diminutive running mate.
Mr Osinbajo had likewise abandoned his traditional flowing robes but looked more relaxed in a smart, Western business suit.
For several months in 2017, it seemed as if the pair's campaign slogan -- "Change" -- could well mean Mr Osinbajo replacing Mr Buhari as head of state.
Mr Buhari spent months undergoing medical treatment at a London hospital, stoking fears his undisclosed condition was terminal.
Mr Osinbajo stepped up as acting president and was considered to have acquitted himself well.
It was a far cry from the start of his tenure when he performed largely ceremonial roles, including leading a choir of ex-presidents in a much-mocked YouTube song.
Beyond the obvious gulf in physical stature apparent in the election campaign poster, there are striking differences between the pair.
Mr Buhari, a Hausa-speaking Fulani from Muslim-majority northern Nigeria, is a straight-backed, no-nonsense former army general who headed a military government in the 1980s.
He has frequently appeared ill at ease with public speaking and has ruled with a close-knit, tight-lipped inner circle that ministers complained left them shut out.
Mr Osinbajo, in contrast, from Nigeria's Yoruba heartland in the southwest, is a partner in a law firm, Pentecostal church pastor and a respected university lecturer.
While the President has often been seen as dismissive of critics, with little time for dissent, Mr Osinbajo, 61, has shown a more listening ear and consensual style.
Mr Buhari has been seen little outside his official Aso Rock residence in the capital, Abuja, barring brief appearances at campaign rallies.
The outgoing Osinbajo in contrast is a more visible presence and is regularly seen touring the country, meeting and talking to ordinary Nigerians.
London School of Economics graduate Osinbajo has been closely involved with trying to boost Nigeria's economy after it plunged into recession in 2016.
In February 2017, he endorsed a move by the Central Bank of Nigeria to relax foreign exchange restrictions imposed because of a shortage of currency caused by the slump.
Elsewhere he has spearheaded attempts to try to make Nigeria more attractive to visitors, and crucially overseas investors, by relaxing visa entry rules.
He has also pushed grassroots government schemes to alleviate poverty and promote business.
How far Mr Osinbajo has been acting on his own initiative or implementing the wishes of Mr Buhari and his inner circle is unclear.
During another Buhari absence in August 2018, he sacked the head of the intelligence service after security personnel staged a brief "takeover" of parliament.
Otherwise, he is largely a technocrat who cut his political teeth under the former Lagos state governor Bola Tinubu, serving as his justice commissioner from 1999 to 2007.
Mr Osinbajo played a key role in drafting the APC manifesto that was successful in wresting power away from the Peoples Democratic Party (PDP) for the first time in 16 years.
Should the ageing Mr Buhari secure a second, four-year term, it's likely Mr Osinbajo will play a bigger role, effectively becoming the public face and voice of the President.
He and Peter Obi, the PDP candidate Atiku Abubakar's pick for vice-president, are both politicians from a younger generation, free from the baggage of Nigeria's troubled past.
Mr Osinbajo has strong political stock -- his wife, Oludolapo, and the mother of their three children, is a granddaughter of the independence movement leader Obafemi Awolowo.