Venezuela's National Assembly has met to choose its leader, a possible stand-in for President Hugo Chavez who is in Cuba following cancer surgery.
The assembly re-elected the incumbent Diosdado Cabello, a leading ally of Mr Chavez.
Opposition leaders are calling for new elections if the president cannot be sworn in for his new term on Thursday.
In such a situation, Mr Cabello would become caretaker president pending the outcome of the vote.
Vice-President Nicolas Maduro has dismissed the opposition's calls, saying the Supreme Court can swear in Mr Chavez at a later date.
Mr Cabello's re-election was expected in the National Assembly, which is dominated by Mr Chavez's governing United Socialist Party of Venezuela (PSUV).
"The president will continue being president beyond January 10, nobody should have any doubt about that," Mr Cabello said after his election, adding: "We will never defraud the people."
Mr Maduro watched the vote and debate from the balcony of the chamber.
The BBC's Sarah Grainger in Caracas says Mr Cabello finds himself in a position of great power and influence.
Analysts say he is seen as a political rival to Mr Maduro, whom Mr Chavez has named as his preferred successor.
However, both men have vowed to maintain unity in the PSUV. They both visited Mr Chavez in Cuba earlier in the week, along with several other dignitaries.
Hundreds of Chavez supporters rallied outside parliament on Saturday following an appeal by Mr Cabello.
Information Minister Ernesto Villegas, who was among the first government officials to arrive for the vote, said: "There is a clear leadership here by Comandante Chavez who is so responsible that he has even studied the worst case scenarios.
"We have a president who has been elected from 2013 to 2019... and that will be perfectly fulfilled. Chavez is the president of Venezuela. There is no other."
Experts have different interpretations of what it would mean if Mr Chavez misses his inauguration.
Some in the opposition say that if Mr Chavez is still in Cuba, power should pass to the head of the National Assembly and new elections should be held within 30 days.
But Mr Maduro has insisted that Thursday is not a fixed deadline and that there was no reason to declare Mr Chavez's "absolute absence" from office.
"The formality of his swearing-in can be resolved in the Supreme Court," he said.
"The president right now is president."
Mr Chavez - who was re-elected for a fourth term in October - has not been seen in public since his latest round of surgery more than three weeks ago.
Mr Villegas said on Thursday that the president had suffered complications due to a lung infection and had a "respiratory insufficiency".
--Courtesy of BBC News