His background suggests he may be more comfortable as a pragmatic negotiator than a charismatic leader. Born in 1962 into a leftist family as the son of a union leader, Maduro began his political career as president of the student union at Jose Avalos high school in El Valle, a working-class neighbourhood on the outskirts of Caracas.
Records show he never graduated, but he was remembered as an imposing and conciliatory figure.
"He would address us during the assembly to talk about students' rights and that sort of thing. He didn't speak much and wasn't agitating people into action but what he did say was usually poignant," says Grisel Rojas, a former classmate who is now the school's principal.
He was a rock music enthusiast in his teens – with Led Zeppelin among his favourites – and reportedly considered a career in a band. Instead he joined the ranks of the Socialist League and worked as a bus driver for the Caracas Metro company, where he followed in his father's footsteps and founded one of the company's first informal labour syndicates at a time when the company banned unions.
During the early 1990s Maduro became a member of the MBR-200, the civilian wing of Chávez's insurrectional military movement, often campaigning for the release of Chávez, who was in jail for leading the failed 1992 coup.
Maduro became increasingly acquainted with other members of the growing Chávista political movement and helped found the Movement of the Fifth Republic under which Chávez ran for president in 1998. During this time he met Cilia Flores, who headed the legal team that won Chávez his freedom in 1994 and later became his wife. Flores is currently the country's attorney general.
After Chávez came into power in 1998 Maduro's political ascent remained steady. In 1999 he was part of the team that drafted a new constitution and went on to serve as deputy at the national assembly until 2000, when he moved on to preside over the legislative body.
In 2006 Chávez named Maduro minister of foreign affairs, a post from which he at times continued Chávez's incendiary rhetoric. At a regional summit in 2007 he called the then US secretary of state, Condoleezza Rice, a hypocrite and compared Guantánamo to atrocities not committed since Hitler's time. Rice had criticised the Chávez government for closing down a private TV station
But Maduro has also succeeded in patching up strained relations with neighbouring Colombia. "Nicolás is one of the strongest and best-formed figures that the PSUV [Venezuela's socialist party] has. He was a union leader and that has given him incredibly negotiating abilities and a strong popular support. Additionally his time in diplomacy has polished him and given him exposure", says Vladimir Villegas, who knows Maduro from their student days and served under him at the foreign ministry.
While some see Maduro as an affable and approachable man of the people, others fear he will strengthen the country's pro-Cuba ties – he is a longtime friend of the Castros – and deepen the region's anti-American sentiment.
Javier Corrales, a professor of political science at Amherst College in the US, says: "Maduro is the Revolution's most Janus-faced character. On the one hand he is one of the PSUV's most convinced leftist, anti-imperialist radical, and on the other he can be soft-spoken and conciliatory. He is the architect of the remarkable turnaround of relations with Colombia in the last two years".
Last October he was named vice-president by an ailing Chávez shortly before the president flew to Cuba for emergency cancer surgery.
In December last year Chávez gave Maduro the ultimate endorsement: "My firm opinion, as clear as the full moon – irrevocable, absolute, total – is … that you elect Nicolás Maduro as president," Chávez said in a dramatic final televised speech. "I ask this of you from my heart. He is one of the young leaders with the greatest ability to continue, if I cannot."
It fell to Maduro on 5 March to announce to Venezuelans that their leader was dead, and he presided over the late president's funeral.
Although he has since tried to adopt a similar style to Chávez, analysts believe that the former negotiator from the union movement will adopt a more conciliatory approach than the former lieutenant colonel from the military.
But that has still to be proved. His narrow margin of victory in Sunday's election could either force him to address the concerns of the opposition or lead to heightened tension.
With tough measures also likely for the economy, Maduro will have to work hard to maintain the unity of his own coalition. Potential rivals, such as Diosdado Cabello, the speaker of the house who has close ties to the military, have backed him as a candidate. Now they must back him as a president.
Read more: Who is Nicolás Maduro? Profile of Venezuela's new president | World news | guardian.co.uk
