KISUMU, Kenya (Reuters) - Nervous Kenyans stockpiled food and water on Monday and police prepared emergency first aid kits as families headed to their ethnic heartlands on the eve of an election many fear could descend into violence.

Opposition leader Raila Odinga, 72, who lost elections in 2007 and 2013, has already said President Uhuru Kenyatta, 55, can only win if his ruling Jubilee party rigs the vote, a stance that increases the chances of a disputed result and unrest.

Opinion polls before Tuesday’s presidential election put the pair neck-and-neck. A run-off is possible if neither gains a 50-percent-plus-one majority. Kenyans will also vote for members of parliament and local representatives.

In 2007, Odinga’s call for street protests after problems with the vote count triggered a widespread campaign of ethnic violence in which 1,200 people were killed and 600,000 displaced.

The violence also hammered East Africa’s biggest economy as regional trade ground to a halt and tourists, the biggest source of foreign exchange, canceled holidays.

Much of the killing a decade ago was in Kisumu, a city of a million people, most of them from Odinga’s Luo tribe, on the shores of Lake Victoria.

On Sunday, its markets and shops were packed with customers stocking up on last-minute essentials.

“We are fearful because before there was rigging and that led to violence,” said orange seller Christine Okoth.

Wilson Njenga, a central government official overseeing the western region, said police had received disaster equipment including first aid but insisted it was all part of normal contingency planning.

“We don’t want to be caught flat-footed,” he told reporters.

On the campaign trail last week, Odinga told Reuters that Kenyatta could not win without cheating, a message that has fired up supporters in his back yard, where some talk openly of violent confrontation.

“If he doesn’t win, we are going to the streets and we’ll demonstrate,” said 28-year-old Kisumu potato seller Ruth Achieng. “The ones that die, we’ll just bury them and life will go on.”

First results are not expected before Wednesday, but a very close race might mean as many as three days before a winner emerges. Officially, election authorities have up to a week to declare the outcome.

In Nairobi, some shop keepers closed early, pulling down steel shutters or moving stock away from window displays. Despite the jitters, Kenya’s currency, the shilling, has held steady around 104 to the dollar for several weeks.

Kenyatta, who six years ago was sitting in the dock in The Hague on charges of crimes against humanity for orchestrating the 2007 violence, urged a peaceful vote and outcome.

“No matter the result of this election, we must stand together as one people. Above all, we must reject intimidation. We must reject violence or any attempt to divide us,” he said in a televised national address. “We are all Kenyans.”

The case against him collapsed in 2015 for lack of evidence.

Slideshow ( 14 images )

PROTESTS BLOCKED

Going back to rural roots to vote is a long-standing Kenyan tradition, driven by a desire to catch up with friends and family as well as choose a suitable local political representative.

More recently, fear of unrest has become a factor.

In all, 150,000 security personnel including park rangers have been called up to maintain order across the country, including preventing demonstrations in hotspots immediately before or after the polls.

Slideshow ( 14 images )

In Kisumu, where many people feel neglected by a central government led by a president from the Kikuyu ethnic group since 2002, County Commissioner Mohamed Maalim said spontaneous protests near election day had been banned.

Such edicts are likely to fuel opposition accusations of intimidation and dirty tricks by the security forces.

“I have never seen this level of intimidation by the state against the electorate,” 71-year-old Senator Peter Anyang’ Nyong’o, an Odinga ally running for Kisumu county governorship, told Reuters.

Hate-speech has been notably absent from large public speeches in both campaigns - an important difference from 2007. However, two incidents in the last week have put the nation of nearly 50 million on edge.

A senior election official was found tortured and murdered a week ago, and on Friday two foreign political advisers to Odinga were arrested and deported by plain-clothes police.

While some Kisumu residents said they were headed to villages west of the city to vote, members of Kenyatta’s Kikuyu ethnic group headed the other direction, away from Odinga’s strongholds.

One supermarket manager who asked not to be identified said suppliers of televisions and furniture had halted deliveries over the past week due to fears of looting.

“They fear to come to this side of the country,” the manager, a Kikuyu, said. He had already sent his family to a Kikuyu-majority city and would be joining them in the evening, he added.

For graphic on Kenya election frontrunners, click tmsnrt.rs/2vENDRp