President Santos has recognized Mr Maduro's election victory and attended his inauguration last month.
On Thursday, Venezuelans queuing to view Mr Chavez's body chanted: "With Maduro, the people are safe!"
BBC: Venezuelan parties gear up for polls after Chavez death
The official count indicates Mr Maduro won 50.8% of votes to Mr Capriles's 49.0%.
Opposition leader Henrique Capriles has challenged Mr Maduro's narrow victory, calling for a vote-by-vote recount.
As the news of Mr Maduro's victory emerged, celebrations erupted in the capital, Caracas.
But the electoral authorities said Socialist Nicolas Maduro would be confirmed as the winner.
Even before he deals with Venezuela's mounting problems, Maduro faces a challenge to his victory.
Chavez's public remarks supporting Maduro likely bolstered support for him among fervent Chavistas, Corrales said.
Maduro promised to expand anti-poverty programs, but without explaining how he'd pay for them.
He named Mr Maduro as his preferred successor following the recurrence of his cancer.
Maduro said that reading of the constitution is false, and that the swearing-in date is flexible.
Capriles said Maduro would have to first register as a candidate and then campaign.
CNN: Venezuela's vice president sworn in as interim president
Maduro did not say when Chavez's final resting place, at a military museum, will be ready.
Chavez was a "true son of Christ" who taught the country love and forgiveness, Maduro said.
As the new president, Mr. Maduro will need all the help he can get.
Maduro made no mention of running for election in his public comments on Tuesday.
Maduro announced that a former vice president, Elias Jaua, will begin serving as foreign minister.
On Wednesday, Maduro said Chavez is undergoing "extremely complex and tough" treatments, which he didn't specify.
"We're more unified than ever, " Vice-President Maduro said upon his return to Venezuela from Cuba.
It is the right to do that, without due process, that Mr Maduro is now challenging.
On Tuesday, Vice-President Nicolas Maduro said Mr Chavez was in "a complex and delicate post-operative state".
But Mr Maduro gave very little further detail about the condition of Mr Chavez.
Mr Maduro subsequently became deputy speaker and later speaker of the national assembly until 2006.
Two US diplomats had been expelled from the country for spying on Venezuela's military, Mr Maduro added.
Mr Maduro said the government would not be blackmailed, and he called on Venezuelans to remain peaceful.
Mr Maduro had been serving as acting president since Mr Chavez died of cancer on 5 March.
BBC: Chavez heir Maduro wins Venezuela presidential election
Mr Maduro read from the letter, which contained flowery language and literary quotes, for about 15 minutes.
BBC: Venezuela VP Maduro reads out 'Chavez letter' at summit
"We have to continue to rise above every provocation with peace, peace, peace and peace, " Maduro said.
Still, he noted, Maduro is a former union official, not the paratrooper military officer that Chavez was.
CNN: Venezuela's vice president sworn in as interim president
Venezuelan President Hugo Chavez is "battling for his health, for his life", his deputy Nicolas Maduro says.
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