Each of the three frontrunners in Nigeria’s hotly contested presidential election claimed they are on the path to victory on Monday, as preliminary results trickled in two days after Africa’s most populous nation went to the polls.

Only one of Nigeria’s 36 states has officially announced results, with the ruling party’s Bola Tinubu winning by a wide margin in Ekiti state, yet each party said it was on track to winning.

On Monday there were three front-runners in the 18-party race: Tinubu, the main opposition party’s Atiku Abubakar and Peter Obi with the Labour Party.

A winner is not expected to be announced until at least Tuesday. After the previous presidential election, it took four days for officials to declare a victor.

A runoff election will be held if no candidate secures at least one-quarter of the votes from two-thirds of Nigeria’s 36 states and the capital city, in addition to receiving the highest number of votes.

There were fears of violence on Election Day, from Islamic militants in the north to separatists in the south, but voting was largely peaceful Saturday.

 However, observers said there were at least 135 critical incidents, including eight reports of ballot-snatching, that undermined the legitimacy of the election.

There were also widespread delays, blamed by officials and observers on logistical issues as well as the upheaval created by a redesigned currency that has left many residents unable to obtain bank notes.

After Tinubu’s victory in Ekiti state, the incumbent party said it was on course to stay in power.  “If the information we are beginning to receive from various parts of the country is anything to go by, one has every reason to be optimistic that our candidate will win,” Abdullahi Adamu, the party chairman, told the state-run News Agency of Nigeria.

The Labour Party also claimed that it is winning.

“We are far ahead and we are already leading and we are winning in 24 states,” said Yunusa Tanko, spokesman for the Labour Party.

 Its candidate, Obi, is a surprise frontrunner in what is usually a two-horse race, with his popularity surging in polls weeks ahead of the vote.

The party accused election officials of not being present in their strongholds and said some of their supporters were denied the opportunity to vote.

As the full results haven’t been released yet, analysts caution that early unsubstantiated claims of victory will do nothing but deepen public mistrust of the electoral process and undermine the legitimacy of the polls.

“The claims by the three parties aim to motivate their voters who are urged to protect ballot boxes from rigging. But the unsubstantiated claims of victory increase the risk of protests, both peaceful and violent by disappointed voters,” said Mucahid Durmaz, senior analyst at Verisk Maplecroft, a global risk intelligence company.