Venezuela’s opposition rejoiced after its shock triumph in legislative elections and waited anxiously for the final tally to see whether it secured a two-thirds supermajority that could dramatically wrest power from President Nicolas Maduro after 17 years of socialist rule.

The Democratic Unity opposition alliance declared Monday that it won the minimum number of seats needed to initiate a process to remove Maduro. But the National Electoral Council was slow to publish results despite the efficiency and transparency promised by the country’s electronic voting system, and more than a full day after polls closed two races remained undecided.