Anti-government demonstrators hold candles during a vigil in honor of those who have been killed during clashes between security forces and demonstrators in Caracas, Venezuela, on July 31. (Ariana Cubillos/AP)

Results from a controversial election for a new Venezuelan political assembly were “manipulated” and are off by at least 1 million participants, the company that provided the voting system said Wednesday.

The disclosure came as Venezuela braced for a pivotal moment in its descent toward full authoritarian rule. Voters on Sunday elected 545 pro-government legislators who will sit in a new ­super-congress vested with vast powers.

Late Wednesday, President Nicolás Maduro announced that their official installation would take place Friday, a day later than anticipated, in the same neoclassical building in central Caracas that already houses members of the opposition-controlled legislature elected in 2015. It remained unclear whether some of the newly minted officials would still try to enter the building Thursday.

Several opposition lawmakers had initially vowed to make a defiant stand inside the chamber when the newcomers arrived. But amid growing internal divisions, at least some in the opposition were apparently changing tactics. The plan, according to two opposition legislators, was to instead launch a protest march toward the assembly building.

“I think the public is aware of our capabilities,” opposition lawmaker Juan Requesens said. “Unless we armed ourselves to defend the space, we wouldn’t be able to do it.”

Other opposition lawmakers began to suggest that both sides might be able to share the building.

The standoff loomed as Antonio Mugica, chief executive of London-based Smartmatic, which has provided technology for Venezuelan elections since 2004, said it detected an inaccurate turnout figure Sunday through the automated balloting system. Venezuelan authorities had said more than 8 million people cast ballots, more than the number of people who voted against the new assembly in an informal referendum last month.

“With the deepest regret, we have to say that the turnout data presented on Sunday, July 30, for the constituent election was manipulated,” Mugica said at a news conference in London.

His company’s analysis of the data, he said, suggested the number was off by “at least 1 million.”

Tibisay Lucena, the pro-Maduro president of Venezuela’s election council, dismissed the allegations and threatened to sue Smartmatic.

“It’s an irresponsible allegation with estimates that aren’t based on the data,” Lucena said in a televised statement.

The company’s charges add to growing allegations of massive irregularities in Sunday’s election, which was condemned internationally. The Trump administration, which slapped sanctions on Maduro on Monday, described it as a “sham election.” A host of Latin American nations, including Brazil, Argentina, Peru and Colombia, have called the vote illegitimate.

The European Union on Wednesday issued a statement saying its members would not recognize the new Constituent Assembly.

In a country suffering food shortages and a deepening economic collapse, government channels on Wednesday showed celebratory images of the new assembly’s members being announced to wild cheers from crowds adorned in red T-shirts and Venezuelan flags. Maduro, the anointed successor of leftist firebrand Hugo Chávez, who died in 2013, has portrayed the new assembly as the cornerstone of an effort to funnel more power and money directly to the people, including to slums.

Senior government officials have dismissed allegations of fraud, saying they came from enemies of Venezuela’s socialist system.

In a sense, there was no way that the government could lose Sunday’s vote. All candidates, including the wife and son of Maduro, were backers of the socialist administration. There was also no voter-participation threshold needed for the outcome to be deemed valid.

But generating a high turnout was considered vital to proving public enthusiasm for the new Constituent Assembly, which gives the government effective control over all branches of government. Opinion polls show the new body and Maduro are deeply unpopular.

The government claimed a turnout of 41.5 percent of eligible voters — more than 8 million votes. On Wednesday, the Reuters news agency reported that it had reviewed internal electoral commission data showing that only 3.7 million people had voted by 5:30 p.m. Most polling stations closed at 7 p.m., but some stayed open later.

On Wednesday, there were more signs of broadening divisions among the opposition on the best path forward.

Henry Ramos Allup, secretary general of the Democratic Action party, announced that his candidates would compete in state elections, initially scheduled for December, despite the allegations of government fraud in the recent balloting. He also backed away from a plan, supported by some in the opposition, to form a parallel government to challenge Maduro.

“Our strategy has always been respect for the constitution, institutions, and fight for free elections,” he said. “We cannot ignore that. It’s what the international community backs.”

Rachelle Krygier and Mariana Zuñiga in Caracas and Michael Birnbaum in Brussels contributed to this report.