Venezuelan President Hugo Chavez's opponents blocked him from capturing an overwhelming majority in Venezuela's congressional election, making gains that could challenge the firebrand leader's iron grip on power.

Supporters of Venezuelan President Hugo Chavez react as they listen the results of congressional elections in Caracas on Monday. (Ariana Cubillos/Associated Press)

With the vast majority of votes from Sunday's election counted, Chavez's socialist party won at least 90 of the 165 seats in the National Assembly, while the opposition coalition won at least 59 seats, National Electoral Council president Tibisay Lucena said early Monday. Other seats either went to a small splinter party or had not yet been determined, she said.

Chavez hailed it as a "solid victory" in an online posting on Twitter, but he fell short of his goal of keeping the two-thirds majority that has allowed his allies to push through controversial changes unopposed. Until now, pro-Chavez lawmakers have been able to rewrite laws unopposed and unilaterally appoint officials, including Supreme Court justices and members of the electoral council.

The initial count was announced eight hours after the final close of Sunday's voting. The opposition had demanded electoral authorities release the results after an hours-long wait that put the country on edge.

Lucena said the delay was due to a number of close races.

Voters stood in long lines for the vote, which stirred strong feelings on both side of Venezuela's deep political divide and was seen as a critical referendum on Chavez's popularity ahead of the 2012 presidential election.

Ramon Guillermo Aveledo, leader of the opposition coalition, called the delayed results "inadmissible." He said according to the opposition's tally, anti-Chavez candidates had garnered more than half the popular vote.

Before the vote, the opposition had criticized an election law passed by Chavez's allies that redrew some legislative districts and gave greater weight to votes in rural areas, where the president remains more popular. Opposition candidates agreed to participate in the elections and respect the results as long as the vote count was transparent.

Aveledo said areas where the electoral council didn't release results were dominated by the opposition, and he demanded electoral authorities give details on those results before dawn. Aveledo also said the existing "moribund" pro-Chavez legislature shouldn't try push through radical legislation before newly elected lawmakers take their posts at the beginning of 2011.

The opposition, which boycotted the last legislative elections in 2005, dramatically increased its representation beyond the dozen or so lawmakers who defected from Chavez's camp in the current National Assembly.

Voting results slow to come

Many Venezuelans had asked why it took so long to release the results. Chavez had said after casting his ballot that he expected results from the automated vote system to be available before midnight, but they weren't released until after 2 a.m. local time.

Opposition candidates called the vote a crucial opportunity to defend democratic principles and freedoms, saying the National Assembly has been simply taking orders from Chavez for five years.

Since he was first elected in 1998, Chavez has fashioned himself as a revolutionary-turned-president, with a nationalist vision and a deep-seated antagonism toward the U.S. government. He has largely funded his government with Venezuela's ample oil wealth, touting social programs targeted to his support base.

During the campaign, Chavez had portrayed the vote as a choice between his "Bolivarian Revolution" and opposition politicians he accuses of serving the interests of the wealthy and his adversaries in the U.S. government.

Chavez's party mounted an aggressive get-out-the-vote campaign. In Caracas, voters were awakened before dawn Sunday by fireworks and recorded bugles blaring reveille from speakers.