Kenya’s presidential candidates were attempting to win over voters on Saturday, the final day of campaigning before Tuesday’s elections.

President Uhuru Kenyatta again faces longtime opposition leader Raila Odinga, the country’s former prime minister, in a narrowly contested vote which many fear could see violence.

Kenyatta is the son of Kenya’s first president; Odinga is the son of the country’s first vice president.

The country’s 19.6 million eligible voters will also be selecting new MPs, governors, and senators.

Recent elections have been contested and more than 1,000 people were killed in post-election violence a decade ago.

Some in the East African nation have left the capital because of the threat of chaos, while many plan to travel to their home regions elsewhere in Kenya to vote.

The torture and killing in recent days of a key election official in charge of the electronic voting system has some concerned about the possibility of vote tampering.

Al Jazeera’s Catherine Soi, reporting from an Kenyatta rally in Nairobi, said the leading candidates were making last ditch pleas to the electorate.

“[Kenyatta] is campaigning on a platform of economic development and infrastructure investment,” she said. “He says that in the last four and half years his government has been able to provide free maternal health to women, and tarmac hundreds of kilometres of road.”

Al Jazeera’s Mohammed Adow, at an Odinga rally in Kenya’s capital, said there were fears in the crowd about how fair the upcoming vote would be.

“The Odinga camp is very hopeful of victory but they’re telling their supporters they will not allow anything other than free and transparent elections,” he said.

“They want to put pressure on the institutions of government to ensure that the elections are credible,” Adow added.

Meanwhile on Saturday, Kenya’s main opposition party said an American and a Canadian who were assisting its campaign were taken from their homes on Friday and detained.

James Orengo, a senior member of the opposition National Super Alliance, said the detentions took place at around the same time that armed and masked police raided an opposition vote counting centre, intimidating workers and seizing equipment.

A police official said immigration officials were holding the American and the Canadian at Jomo Kenyatta International Airport in Nairobi, the AP news agency reported.