Parties allied to President Hugo Chavez say they have won all 167 seats in the country's parliament, after elections boycotted by the opposition.
Hugo Chavez urged voters to turn out in force
None of the five main opposition parties took part, accusing the electoral body of bias.
Only about 25% of registered voters cast a ballot.
A two-thirds majority in parliament will allow Mr Chavez to remove the current constitutional limit of two presidential terms in office.
But the opposition says the low turnout deprives the election of legitimacy.
"Venezuela is speaking with its silence," said Julio Borges, a prominent opposition member.
BBC Latin America analyst James Painter says the election was essentially about the democratic legitimacy of Mr Chavez, as both sides can claim a victory of sorts.
Attention will now focus on the international observers who are due to pronounce on the fairness of the vote, he adds.
The Fifth Republic Movement, Mr Chavez's party, won 114 seats in the 167 single-chamber National Assembly, according to senior party member, William Lara.
Polling stations in some urban areas were almost empty.
He said the remainder of seats had been won by allies of the president.
Previously, Mr Chavez's supporters had only held 89 seats.
About 14.5 million Venezuelans were eligible to vote.
The BBC's Greg Morsbach in Caracas says people queued to vote in deprived parts of the city, where support for the president is usually strong.
Polling stations in middle class urban areas were almost empty, our correspondent says.
The National Electoral Council said 556 out of 5,500 candidates had pulled out of the congressional vote.
Opposition leaders accused the electoral authorities of favouring pro-government candidates.
Mr Chavez condemned the boycott as a Washington-backed plot to destabilise his government - a charge the US rejected. "These old parties, they are already dead, but they are still hanging on, resisting death," Mr Chavez told reporters after voting.
"Now they've accelerated their own demise."
The government deployed thousands of soldiers nationwide to maintain order during the vote.
Hours before voting began, an oil pipeline in the west of the country was damaged in a blast which officials claimed was a sabotage attack.
The poll is being monitored by observers from the European Union and the Organisation of American States.
However, the opposition group Sumate alleged widespread irregularities.