The Democratic Republic of Congo is scheduled to release election results Thursday after a two-day delay that has intensified tensions between the government and opposition leaders. On Tuesday, Congo's election commission announced that it was postponing announcing the results by 48 hours. "People stayed up until after midnight early Thursday waiting for the results," said Herman Nzeza, the Congo representative of FreeFair DRC, a nonpartisan group that raises awareness of the election. "They normally announce them at night, so the streets were empty. People were waiting for them to be announced on state television." Nzeza, who is based in the capital of Kinshasa, said there is no set time frame for the announcement, but citizens expect it before midnight local time. Opposition leaders have accused the election commission of conducting a botched poll after preliminary results showed incumbent President Joseph Kabila in the lead. Etienne Tshisekedi, the main challenger, has warned that the opposition will not accept the election outcome amid claims of ballot stuffing and manipulated voter lists. Kabila, 40, took over after his father's assassination in 2001 and was later elected in Congo's first democratic election five years later. Frontrunner Tshisekedi, 78, has gained popularity in the sprawling capital of Kinshasa for speaking out against the nation's autocracies and has been a fixture in the nation's politics for three decades. The election commission said Tuesday that Kabila was leading with 49% while Tshisekedi had 34% with nearly 90% of the vote counted, according to Nzeza. "Expectations are high. Tensions are very high," he said. "The opposition wants to win. It's now or never. Tshisekedi is already considering himself president. We don't know how all sides will react, if their candidates don't win." Analysts fear the election outcome could plunge the nation into chaos again years after a 1998-2003 conflict that left 5 million dead as a result of fighting, diseases and starvation. Clashes have erupted after the vote, with at least 18 people killed in a week of election-related violence, Human Rights Watch said Friday. Stability in Congo -- which borders nine mostly vulnerable countries -- is vital to Africa's Great Lakes region. The years of war affected at least six neighboring nations, some of which are still battling rebel movements spawned during the conflict. Despite Congo's vast resources including cobalt, gold, copper and tantalum, the fledgling democracy is mired in poverty and conflict especially in its eastern region, a hot spot for the so-called "conflict minerals" that activists say are used to fund rebel movements in the area.