NAIROBI, Kenya — The two men were political allies.

But they had a falling out over the direction of newly independent Kenya — especially over land and power — and became bitter adversaries.

Now their sons are fighting a modern adaptation of the same battle as they vie to lead the country, pushing one of Africa’s youngest and most vibrant democracies to the brink of a constitutional crisis.

“History is not exactly repeating itself,” said Maina Kiai, a human rights lawyer in Kenya, describing the eerie political parallels between past and present, “but it certainly is rhyming.”

Politically, Kenya is deeply — and evenly — divided between Uhuru Kenyatta, the president, and his longtime political rival, Raila Odinga. In last year’s election, Mr. Kenyatta won slightly more than half the votes, and Mr. Odinga slightly less. Those results were tossed out in a historic decision by the Supreme Court, which cited widespread irregularities.