About 1,500 people were killed in ethnic violence related to the Kenyan vote in December 2007.
If large-scale violence does explode in the East African state, whose $34 billion economy is the largest in the region and which was once considered one of the continent's most stable countries, it could destabilize a fragile region that's on the cusp of an oil and natural gas boom.
"A return to chronic political violence in Kenya, even if temporary, could disrupt the flow of investment and trade to Kenya and complicate Nairobi's bid to consolidate its position as the political and economic hub of East Africa," the U.S. global security consultancy Stratfor observed.
"The run-up to the election has shown that Kenyan politics remains an ethnically driven power struggle to control the country's resources," London's International Institute for Strategic Studies noted in an analysis published Tuesday.
"Violence is highly likely, particularly before and after the run-off vote. Localized violence has already begun ....
"Vote rigging is expected but will be more difficult than in 2007. However, the predominance of ethnic politics means that Kenya will continue to be at risk of significant violence," the think tank concluded.
In March, Kenya's estimated 22 million voters will elect a new president to replace Mwai Kibaki, of the dominant Kikuyu tribe whose election for a second term Dec. 27, 2007, triggered the tribal violence and took Kenya dangerously close to civil war.
Supporters of his rival, Raila Odinga, mainly from the Luo and Kalenjen tribal groupings, claimed massive vote-rigging, widely confirmed by international observers who said both sides were involved in that.
That bloodletting broke out in early 2008 and raged for two months, particularly in the volatile Rift Valley.
On top of the death toll, some 600,000 Kenyans were displaced, and many of them remain so.
Former U.N. Secretary-General Kofi Annan mediated a power-sharing pact between Odinga and Kibaki under which Odinga became prime minister. Odinga is running again in March. Kibaki has to step down.
To this day it's unclear who was responsible for the massacres, during which tribesmen slaughtered rivals with machetes and even bows and arrows, leaving a legacy of deep hatred many Kenyans fear will never be expunged.
Four people have been indicted by the International Criminal Court for organizing the massacres and committing crimes against humanity.
They include Odinga's two key rivals, Uhuru Kenyatta, son of Kenya's founding president and one of the country's richest men, and his running mate William Ruto, a former Cabinet minister dismissed on suspicion of corruption.
The court alleges the two candidates hired criminal gangs who carried out some of the murderous rampages in 2008.
Even so, they're leading most opinion polls. Kenyatta is able to tap into his Kikuyu tribal base. Some 43 percent of registered voters are automatically aligned with him because of ethnic links.
Post-2007, Kenya has introduced strict laws against ethnic incitement under a new constitution in hopes of averting further bloodletting. But the political and tribal enmity between the Kenyatta-Ruto alliance and Odinga is causing deep concern about another spasm of violence.
If Kenyatta wins and refuses to cooperate with the ICC, which observers say is a distinct possibility, Kenya risks international condemnation and economic sanctions that could hit the country hard.
That would be a setback for the United States and Britain, key backers of Kenya, which plays a major role in fighting Islamist militants in neighboring Somalia and is being targeted by them.
Kenyan politicians have long exploited ethnic differences during elections at all levels, a policy that "works for those who engage in it," observed Kenya expert and U.S. academic Jacqueline Klopp.
"Ethnic divisions has shaped Kenyan politics since the country's independence from the United Kingdom in 1963 and have triggered localized violence in every poll since multiparty elections were introduced in 1992," the IISS noted.
In recent months, more than 100 people have been slain in tribal clashes in the Tana River region of southeastern Kenya, where political boundaries have been redrawn for the March elections.
All told, authorities say 450 people have been killed because of political rivalries since early 2012.