US prosecutors have accused Saab of siphoning off $US350 million ($A518 million) from Venezuela via the US in a scheme that involved bribing Venezuelan government officials.
He denies the charge.
Six Venezuelan activists were freed from prison on Wednesday, according to their lawyer and the wife of one of them.
The long-time education campaigners were convicted on conspiracy charges earlier this year and sentenced to 16 years but have proclaimed their innocence.
The administration of US President Joe Biden relaxed sanctions on Venezuela in October in response to an agreement by the government to hold fair elections in 2024.
But the White House had said in recent weeks it was prepared to "pause" sanctions relief unless there was progress on prisoner releases.
Biden, asked about the possibility of a prisoner exchange, told reporters travelling with him in Wisconsin that the situation "looks good".
He added: "It looks like Maduro, so far, is keeping his commitment on a free election. It ain't done yet. Got a long way to go. But it's good so far."
The prisoner swap talks were "mediated" by Qatar, which was asked by both sides to help improve relations between the United States and Venezuela, according to a person briefed on the agreement.
Qatar's chief negotiator met Maduro last week.
Although the releases could be seen as a step by Maduro to comply with US demands, the return of Saab would mark a victory for Maduro.
Saab has not yet been convicted and his return to Venezuela was previously seen as unlikely.
The United States had given the Venezuelan government until November 30 to make progress on removing public office bans on opposition candidates and start releasing political prisoners and "wrongfully detained" US citizens in order to avoid a reinstatement of sanctions.
Venezuela is allowing opposition candidates to appeal their bans but it had not made much progress on prisoner releases before Wednesday.
Maduro is scheduled to hold an event later on Wednesday although the government has offered no details.
"We want to make sure that our fellow Americans are released. We are also focused on political prisoners in Venezuela and trying to ensure their release," said Antony Blinken, the US Secretary of State, in a press briefing.
"We hope to have some good news to share probably later today."
The Associated Press reported that the United States has already released Saab.
A lawyer for Saab declined to comment.
Saab has pleaded not guilty, and his trial date had not yet been set.
Those expected to be freed include opposition-linked Venezuelans who have been in jail for some time, the sources said.
Others involved either with the campaign of opposition presidential candidate Maria Corina Machado or the organisation of the opposition's October primary would be freed or their arrest orders withdrawn.
US citizens who have been classed by the US government as "wrongfully detained" include Eyvin Hernandez, Jerrel Kenemore, Joseph Ryan Cristella and Savoi Wright.
Hernandez and Kenemore were arrested near Venezuela's border with Colombia in March 2022 while Cristella was arrested in July last year.
The three men were accused of trying to enter the country illegally.
Other US citizens in prison in the South American country include former Green Berets Luke Denman and Airan Berry, who were jailed for their participation in a failed armed incursion in 2020.
