Catholic leaders who mediated a compromise on elections in Democratic Republic of the Congo warned on Monday that the credibility of the long-delayed vote scheduled in December depends "to a great extent" on the presence of national and international observers - and that "bias" will keep the country in crisis.Monsignor Marcel Utembi, president of the National Episcopal Conference known as CENCO, encouraged the government to implement all provisions of the December 31, 2016 agreement that it mediated - especially de-escalation measures - and to take into account concerns of opponents and civil society."If elections are biased, they will keep us in a crisis ... and the lack of clarification in the situation will cause grave problems," he warned.The vast, mineral-rich nation is under pressure to ensure free and fair elections.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and FacebookPresident Joseph Kabila, who became DRC's leader in 2001 after the assassination of his father, former President Laurent Kabila, by law could not run again after his mandate ended in December 2016. But he remained in office because of delays in holding elections, which sparked deadly protests.Kabila announced last month that he would not try to stay in office, giving one of Africa's most turbulent nations the opportunity for what could be its first peaceful, democratic transfer of power. But there are concerns, raised not only by CENCO but by US Ambassador Nikki Haley and other council members, that Kabila will try to ensure that his chosen candidate, former interior minister Emmanuel Ramazani Shadary, will win.Utembi outlined a series of recommendations from CENCO to the government and the Independent Electoral Commission known as CENI to ensure fair elections including: agree to facilitate national and international observation of the elections; reach consensus on whether to use voting machines; and prevent "arbitrary application of rules to certain candidates who wish to run."The opposition and some in the international community, including the US, are objecting to the planned use of electronic voting machines despite warnings from watchdog groups that transparency and credibility could suffer. In response, DRC's government declared it will fund the election itself and has not asked for help from the UN peacekeeping mission in the country.Haley raised a series of "red flags and unanswered questions" at Monday's council meeting including about the voting machines.She asked: Will there be enough machines? Can authorities recharge them with only a 12-hour battery life? Have election organisers widely tested them? How is the electoral commission going to transport election materials to more than 90 000 polling places? Will voters know how to use touchscreens? Are organisers preparing paper ballots as a back-up?"Paper ballots were good enough to get president Kabila elected, and they should be good enough as a fail-safe to elect his successor," Haley said, adding that if the president was at the UN today she would ask whether self-financing the election and doing it without help from the UN peacekeeping mission is possible."It can't help but raise suspicion when the Congolese government refuses the assistance that would help make free, fair and credible elections a reality, but continue to take the humanitarian assistance that so many of us continue to give them," she said.Haley said other "red flags" add to US suspicions including the electoral commission's August 24 decision "to disqualify some opposition presidential candidates for what appear to be political reasons."Opposition candidates must be allowed to speak freely, without fear or harassment so that all parties compete "on a level playing field," she said.With 118 days left before the election, Haley said, "these problems are fixable," and the hopes of 80 million Congolese citizens for a free and fair vote rest on the decisions the government and electoral commission make in the days and weeks ahead.Leila Zerrougui, the UN envoy for DRC, told the council by video from Kinshasa that the lack of consensus on using voting machines and the absence of a definitive list of candidates because of appeals to the Constitutional Court are causing discord, she said. The list is expected on September 19 after appeals are heard.The court's review and appeals process "will be key to the legitimacy of the electoral process going forward," Zerrougui said. "A lack of confidence or a perceived lack of credibility in the CENI or in the decisions of the Constitutional Court would only serve to heighten tensions in this process."She warned that any indication that CENI went beyond its mandate in interpreting the electoral law and determining the eligibility of candidates "would only undermine confidence in the process as a whole."DRC's UN Ambassador Ignace Gata Mavita responded to scepticism and questions saying CENI has been carrying out an awareness-raising campaign on the use of voting machines, is working on the issue of 6 million voters registered without fingerprints, and the government remains determined to finance the elections."Our country remains open to support from other partners as long as this support comes without preconditions and respects the sovereignty of the country," Gata Mavita said.