Democratic Republic of Congo election officials are meeting later to discuss extending Thursday's deadline to register candidates for June's polls.
DR Congo's infrastructure has been wrecked by war and misrule
By Wednesday morning, only 100 people had paid the required $250 to run for the 500-seat parliament.
Incumbent Joseph Kabila, 34, has become the 10th candidate to register for the presidential contest.
The polls are to be the first multi-party polls in 45 years, ending a post-war transitional period.
On Wednesday, thousands of supporters of veteran opposition leader Etienne Tshisekedi demonstrated in the capital, Kinshasa, demanding a repeat of voter registration.
Mr Tshisekedi is one of the high-profile politicians still to formally submit his papers and pay the non-refundable $50,000 registration fee.
Having boycotted earlier stages of the electoral process, his party is not represented on the electoral commission.
Visiting UN head Kofi Annan has urged President Kabila and others to make the voting as free and fair as possible.
After years of war and misrule, there is little infrastructure in a country the size of Western Europe.
There are no road or rail links from one side of the country to the other.
President Joseph Kabila
Vice-President Jean-Pierre Bemba, former rebel leader
Catherine Nzuzi wa Mbombo, standing for Mobutu's PRM party
Pierre Pay Pay, ex-finance minister and central bank governor under Mobutu
Vice-President Azarias Ruberwa, former rebel leader
Etienne Tshisekedi, veteran opposition leader
Mr Annan also said the polls pose "major logistical challenges, if not nightmares".
He later said the difficulties "should not be insurmountable - if the will is there, and the leaders put the interest of the nation and the people ahead of short-term concerns."
Vice-President Azarias Ruberwa of the former Rwandan-supported RCD rebel group has not yet registered despite being expected to stand.
Jean-Pierre Bemba of the former Ugandan-backed MLC rebels has submitted his papers and paid the deposit.
There is one female candidate - Catherine Nzuzi wa Mbombo, a former governor of Kinshasa, who is standing on behalf of the former ruling PRM party, founded by ex-President Mobutu Sese Seko.
The largest United Nations peacekeeping force - nearly 17,000 troops - is tasked with ensuring the elections go smoothly.
The UN secretary-general says a planned deployment of European Union troops is also expected to act as a rapid reaction force during the polls.
More than 1,000 people are estimated to be dying each day in the country, where fighting - particularly in the east - continues.
Hostilities between rival militias and government forces continue to force hundreds of thousands of displaced people from their homes.