Former Democratic Republic of the Congo  Vice President Jean-Pierre Bemba on Wednesday arrived in the capital Kinshasa for the first time in a decade to take part in the upcoming presidential elections.

Bemba returned weeks after the International Criminal Court (ICC) overturned his war crimes convictions to submit his credentials to the electoral commission.

He had been in custody in The Hague for 10 years and was convicted in 2016 for having failed to prevent the armed that he led from committing crimes in the Central African Republic that included murder, rape, and pillaging. He had been sentenced to 18 years in prison.

A week ahead of the deadline to file applications for the much-delayed presidential  election , scheduled to be held in December, another prominent opposition leader also announced his return to participate in the political process - a development seen as altering the political calculations in this African nation.

Exiled opposition leader Moise Katumbi announced his plans to return to the country, two years after he fled the country, to seek his party's ticket for presidential election .

Both Bemba and Katumbi, who lead in the opinion polls, stand the risk of being barred from standing for election due to criminal convictions.

Katumbi, a b usinessman and former governor of Katanga region, fled the DRC in 2016 after he was accused of moving against President Joseph Kabila , who is in power since 2001.

Lambert Mende, the Congolese minister of information and communication, told Al Jazeera that the government is not concerned about Bemba's return.

"Congo is his home and it is his right to come back home," Mende said.

Party candidates

The Congolese electoral commission has set August

8 deadline for all political parties to submit applications for their candidates.

The opposition Movement for the Liberation of Congo party has already declared Bemba as their candidate.

Bemba told Al Jazeera that he will be in the country to fulfill his political obligation despite concerns raised about the conduct of the election.

"I never heard from himself [Kabila] that he will hold elections, but I have also never heard that he will not hold elections ... I hope that he will respect the constitution," Bemba said.

"President Kabila is an adversary in politics. The most important to me is what the people of Congo want. If I am doing politics, it's to solve the problems for the people of Congo ...

Of course, I understand that some people may worry about it but they should not. I am just someone trying to find solutions for his country and for the people of his country," he added.

Christopher Harvin, a partner at Sanitas International and Co-Founder of Vanguard Africa, told Al Jazeera that Bemba's return rejigs the country's political space.

"Bemba's return provides the people of DRC hope for change and everyone is eager to see the impact of his return and how it influences the opposition," Harvin said.

On his part, Katumbi - who launched in South Africa the Ensemble [Together] platform to overthrow Kabila - is set to formally begin his campaign process.

Katumbi, seen as the opposition's leading candidate in the election, wants to join forces with other groups.

He was sentenced in absentia to three years in prison for real estate fraud. He denies any wrongdoing, saying the charges were politically motivated.

A constitutional court, manned by two loyalists of Kabila, is expected to rule on their eligibility once they turn in their political credentials to the electoral commission.

'To stand or not'

Civil society groups and leaders, including the influential Catholic bishops, have called for Kabila to hold elections and step aside.

His second term officially ended in 2016 and he is constitutionally ineligible to seek re-election in December's poll, prompting rivals to accuse him of wanting to stay in power.

Kabila has not clearly stated whether he will step down despite appeals from the international community.

"Kabila and his allies are looking for options and so far they don’t have a clear path to stay or leave that is justified by the judicial system, agreed upon by the international community or which provides a safe and secure transition for the DRC's current president," Hansen said.

Prime Minister Bruno Tshibala in June said Kabila will not seek a third mandate in the country's delayed elections, but his ruling coalition has not publicly said he will not stand for re-election.

"We shall choose one... We are on consultation and since you are not a member of the party I will not inform you,"

Mende, the Congolese minister,  told Al Jazeera.

"We shall reach a decision before 8th August." Public opinion

A public opinion poll released on Tuesday revealed that the two opposition leaders, Katumbi and Bemba,  lead a race to replace Kabila as the DRC president.

The poll conducted by the Congo Research Group at New York University and Congolese polling firm, BERCI, shows that 62 percent of people do not trust the electoral commission to conduct a free and fair election.

Harvin said that it is important for the opposition to close ranks to succeed in their quest for leadership change.

"While the opposition has tried to unify many political parties under one band, the opposition is not without significant problems and rivalries. They must continue to overcome their differences in unity to work together for the good of the people and future of DRC," he said.