Kinshasa - Tensions have intensified in the Democratic Republic of Congo ahead of the constitutional end of President Joseph Kabila's second and final term on Tuesday.No elections have been organised and the opposition accuses him of seeking to retain power.Here is a timeline of the crisis in the vast country of 70 million people:Draft law inflames tensionsOn January 17, 2015, parliament adopts a bill that would enable Kabila, who has been in power for 14 years, to extend his term beyond 2016.Kabila's opponents believe he wants to prolong his mandate by making the presidential and parliamentary elections contingent on a new electoral roll, after a census that was set to begin in 2015 but has yet to take place.From January 19-22 clashes between police and anti-Kabila demonstrators erupt in Kinshasa and several other towns. They degenerate into riots and looting, with police using live fire and tear gas. Dozens of people are killed. Speaking from Belgium, opposition leader Etienne Tshisekedi calls on the Congolese people to force a "dying regime" from power.On January 25, parliament votes in favour of a new election law which still leaves doubts over the timetable for fresh polls.In December, the United Nations expresses concern over a government crackdown on opponents, pointing to "arbitrary arrests and detentions, in particular of political opponents, civil society activists or demonstrators".Katumbi declares candidacyOn May 4, 2016, opposition leader Moise Katumbi declares he will stand in the presidential election and is seen as the leading challenger to Kabila. A former Kabila ally, the wealthy businessman joined the opposition in September 2015 after stepping down as governor of mineral-rich Katanga province.Later in May, he leaves for South Africa, ostensibly for medical treatment, after appearing in court twice over alleged use of foreign mercenaries.He is sentenced in June to three years in jail over a separate real estate dispute, effectively making him ineligible to stand.Kabila allowed to stay On May 11, 2016, the Constitutional Court says Kabila can remain in office when his mandate expires, even without being re-elected.On June 10, at a Brussels meeting organised by Tshisekedi, the mainstream opposition decides to set up a new coalition.Tshisekedi returns to Kinshasa in July after two years in Belgium. Speaking before tens of thousands of supporters, he demands the election be held by year's end and the departure of Kabila.Deadly unrest In September, the opposition coalition calls for demonstrations to signal notice to Kabila, three months before his term expires.Violence erupts in Kinshasa on September 19-20 between security forces and youths, leaving several dozen people killed.On December 12 the United States and the European Union impose sanctions on top Congolese officials over the bloodshed.Election put off On October 17 the parliamentary majority and an opposition fringe minority sign an accord pushing the election back to April 2018 and keeping Kabila in place until his predecessor takes over. The mainstream opposition continues to demand the departure of Kabila at the end of his mandate.Last-ditch mediation On December 8 Congo's episcopal conference CENCO launches talks aimed at a deal on setting up a transition authority until a presidential election can be held. It sets a December 16 deadline.But that deadline came and went - and on December 17 Catholic church negotiators announced the talks would resume only a day after Kabila's term ends."There is no deal," said Jean-Marc Kabund, secretary general of Tshisekedi's Union for Democracy and Social Progress (UDPS)."The ruling majority is sitting on its positions and refuses to offer any concessions on matters that require a political response."