NAIROBI, Kenya >> Kenya’s presidential candidates dove into a final day of campaigning today before Tuesday’s narrowly contested election as many worried that the vote could turn violent. The main opposition coalition said an American and a Canadian who were assisting with its campaign had been deported.

President Uhuru Kenyatta, who planned to campaign today in his stronghold of Nakuru city, again faces longtime opposition leader Raila Odinga, whose supporters gathered for a final rally in Nairobi, the capital. Kenyatta is the son of Kenya’s first president; Odinga is the son of the country’s first vice president and has run in vain for the top post in three previous contests.

Recent elections in the East African high-tech and commercial hub have been hotly contested, and more than 1,000 people were killed in post-election violence a decade ago. Kenyatta prevailed over Odinga in a 2013 vote that was mostly peaceful but tainted by opposition allegations of vote-rigging. Former U.S. Secretary of State John Kerry is among the thousands of expected election observers this time around.

Some in the nation of 44 million people have been leaving the capital because of the threat of chaos, while many are simply going home 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.

Today, Kenya’s main opposition party said an American and a Canadian who were assisting its campaign were deported after being taken from their homes on Friday. It was not immediately clear why they had been detained.

A police official earlier said immigration officials were holding the American and the Canadian at Jomo Kenyatta International Airport in Nairobi. The official spoke to The Associated Press on condition of anonymity because he is not authorized to speak with the media.

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

Kenyan police today denied allegations that officers broke into political party offices on Friday, saying no report of a burglary has been made to any police station.