The referendum campaigns of 2005 which pitted then President Mwai Kibaki against his Roads Minister Raila Odinga led to formation of ODM.
Mr Kibaki was supporting the proposed constitution, while Mr Raila was against it.
Then Liberal Democratic Party (LDP) leader, Raila, was in the "No" camp whose symbol was an orange, while Kibaki was in the "Yes" camp represented by a banana.
On November 21, at least 58 per cent of Kenyans rejected the proposed constitution handing Raila's camp victory over Kibaki. The Then Head of State responded by firing all pro-no Cabinet ministers and senior government officials.
Apart from Raila, Kibaki sacked Kalonzo Musyoka (now Wiper leader), Ochillo Ayacko, William ole Ntimama, Najib Balala (Now Tourism Cabinet Secretary), Anyang' Nyong'o (Now Kisumu Senator) and Linah Jebii.
Raila's camp also had the then Opposition leaders Uhuru Kenyatta (now President), William Ruto (now Deputy President) and and Mutula Kilonzo's backing.
But as the leaders were still in a celebratory mood following the victory that was perceived as protest vote against Kibaki's leadership ahead of the 2007 polls, lawyer Mugambi Imanyara grabbed the opportunity and registered ODM as a political outfit.
Raila's camp was outsmarted and had to scout for a different name which saw them register ODM-Kenya.
In a recent interview with The Standard, Mr Imanyara said he was inspired to register the party because of the resounding defeat the banana camp had suffered.
"After the no team won, I knew that the orange was going to transform itself into a political movement. I acted fast and registered the party," he said.
Uhuru would later ditch the Orange team in favour of President Kibaki 2007 re-election bandwagon.
ODM-Kenya remained with Raila, Kalonzo, Musalia Mudavadi, Ruto, Balala and Joseph Nyagah.
However, during this period there were already internal haggles over who was to be the party's presidential flagbearer. In mid-August 2007, the wrangles blew out creating two camps, pro-Raila and Pro-Kalonzo.
It was at that point that the current Makueni MP Dan Maanzo declared that ODM-K belonged to Kalonzo. Raila's camp was left with no party.
"Those who felt left out by Kalonzo's party, including Raila, approached me to give them the party to use as there was little time left. I met with Raila many times and agreed to give him the party," Imanyara said.
Raila, Ruto, Mudavadi, Balala and Nyagah (the pentagon) took over the outfit, leaving ODM-K for Kalonzo and Julia Ojiambo to run for presidency under the party. Kalonzo beat Ojiambo in the party primaries and that made the latter the automatic running mate.
Raila would later win ODM presidential nomination, with Mudavadi as his running mate. Raila and Kalonzo took on Kibaki in a fiercely contested election, whose outcome plunged the country into chaos.
In 2008 ODM held its first elections after the enactment of Political Parties Act, which saw Raila picked as its party leader.
Former Cabinet Minister Henry Kosgey was elected as the party chairman. Apart from Raila, all the other key ODM luminaries have bolted from the party in the last couple of years.
Ruto, Balala and Mudavadi (now Amani National Congress leader) are some of the leaders that have defected from the party after a fallout with Raila at different stages.
The party's immediate former Secretary General Ababu Namwamba is the latest top official to walk out.
ODM National Chairman John Mbadi said some of the leaders bolted out because of power dynamics and not on ideas and principles.
"People come together to form parties not based on ideologies and principles but basically to win power and the moment that power is not won people start to scatter. Because we did not take full government in 2007, it was so easy for the other side which was wielding more power to poach into our team," said Mr Mbadi.
He claimed that Ruto left because of his own political interests and only used the International Criminal Court (ICC) case he was facing to whip emotions of his people.
He, however, admitted the party has suffered because of the bolting by some of the key party leaders during the last 10 years.
"Our politics is still ethnic based so whenever they leave they go with a chunk of supporters from their communities," he added.
The party secretary for political affairs and Ugunja MP Opiyo Wandayi said it was normal for people to defect from such a "giant" political outfit.
"It is natural for a giant political movement such as ODM to lose some members in a period spanning a decade," Mr Wandayi said.
He added: "Likewise, within the same period, it would gain some new members. For ODM it has gained more new members than the ones it has lost." And the party maintains that it is still the largest political party in Kenya.
"The Orange Democratic Movement (ODM) is the largest political party in Kenya born out of a protracted struggle for reforms," The party said in its website.
The party has 78 elected MPs, 17 senators, 16 governors, 15 Woman Representatives, three nominated MPs and 587 MCAs, making it the single political party with the highest number of elected leaders.