Leaders of Venezuela's opposition are claiming victory in Sunday's legislative elections, but official results have not yet been released.
"The results are as we expected. Venezuela won," former presidential candidate Henrique Capriles wrote on Twitter, without stating where he received information about the results.
If the opposition did win the majority of seats, it would be a major setback for the long-dominant socialists who have led the country for 16 years.
Analysts say the vote was essentially a referendum on the socialist economic policies of late president Hugo Chavez and his handpicked successor, current President Nicolas Maduro.
A survey last month estimated that 55.6 percent of voters would back the opposition coalition.
Venezuela has the world's largest oil reserves, but plunging oil prices have left the South American country with one of the world's highest inflation rates, widespread product shortages and long lines to shop for basics.
Opposition leaders have long accused the administrations of Chavez and Maduro of repressing dissenting voices and jailing rival politicians and activists.
In the most recent event to trigger national anxieties ahead of the elections, Venezuelan authorities arrested three people last week accused of killing opposition candidate Luis Diaz in the central state of Guarico.
Diaz was shot in late November while attending a political rally alongside Lilian Tintori, the wife of imprisoned opposition leader Leopoldo Lopez. Government officials denied any link to Diaz's death.
On Saturday, Maduro met with the former heads of state of Bolivia, Colombia, Costa Rica and Spain who are serving as international observers of the election.