By Adam Mynott
BBC News, Nairobi
Kenya's voters now know for certain the candidates who will contest the presidency later this year, with the announcement that President Mwai Kibaki will, as expected, stand for re-election.
Kenyan will vote for a new president in December
His opponents Raila Odinga and Kalonzo Musyoka have already said they are throwing their hats into the ring.
Seventy-five year old President Kibaki declared not only that he would stand again, but he also revealed a new political alliance that would be backing him - the Party of National Unity (PNU).
Mr Kibaki has abandoned Narc (National Rainbow Coalition) which piloted him to victory five years ago, and formed a new party with some interesting bedfellows.
Not least among them is Uhuru Kenyatta, who is the leader of the former ruling party, Kenya African National Unity (Kanu).
A few short months ago, Uhuru Kenyatta and Kanu were linked to the Orange Democratic Movement, an alliance of opposition parties, which successfully campaigned against a proposed new constitution for Kenya.
There are now two opposition ODM political parties
ODM won the constitutional referendum in 2005 and went on to register as a political party.
Subsequent squabbling in the ODM over who would be selected to be the party's presidential candidate split the movement asunder.
There are now two ODMs: ODM - Kenya, Kalonzo Musyoka's party; and ODM, the party of Raila Odinga.
Uhuru Kenyatta found himself left out in the cold, leader of a party that ruled Kenya for nearly 40 years from 1963, first under Uhuru's father, Jomo Kenyatta, the first post-independence president of the country, and then under Daniel arap Moi.
Without sufficient backing to mount a presidential bid, Uhuru Kenyatta has been moving inexorably towards the Kibaki camp for weeks.
When, a fortnight ago, ex-President Moi, who is still a formidable political force, announced that he was giving his backing to President Kibaki it was simply a matter of time before Uhuru Kenyatta did likewise.
This represents an extraordinary political somersault.
Uhuru Kenyatta, leader of the official opposition, who was narrowly defeated by President Kibaki in the election of 2002, is now numbered among his main backers.
Mr Kibaki cited in his speech the achievements of his five-year term
The Kanu chairman has defended his decision on the grounds of national unity.
In a reference to Raila Odinga and Kalonzo Musyoka, Uhuru Kenyatta said, "We should avoid a situation where euphoric monsters gain priority. A nation needs peace and stability and cannot be ruled by euphoria."
Nothing if not realistic, Uhuru Kenyatta has appreciated that Kenya will not be ruled by him for the next five years, but he is doubtless hoping for the reward of a cabinet post if President Kibaki gets back in.
The tectonic plates of Kenyan electoral fortunes are shifting.
They will continue to creak and shudder in the weeks ahead, shunted this way and that by tribalism.
Tribal loyalty remains the dominant factor in Kenyan politics, not the needs and aspirations of the Kenyan people.
As the Daily Nation put it in an editorial: "What, at the moment, seems to matter is the ethnicity of the three candidates, one reason why Kenyans keep voting for the wrong people..."
President Kibaki said he had considered the challenges facing Kenya before deciding to form a new political alliance.
He told a large crowd gathered in the Kenya International Conference Centre, "This is an alliance that is committed continuously to reduce the levels of poverty and ensure every Kenyan has access to food, shelter, health and education."
He immediately went off on the campaign trail to western Kenya, where he will repeat the new Kibaki mantra that Kenya's economy has been transformed under his leadership.
Annual GDP in Kenya is surging ahead.
He also promised good governance.
The word "corruption" did not creep into his KICC address, the evil he promised to get rid of when he became president, but which sits like a cancer in the Kenyan civil and body politic.
His two opponents are also out campaigning.
They each hope their appeal lies in the fact they are "new", though both are, of course, seasoned Kenyan politicians.