Amani National Congress leader Musalia Mudavadi says opposition leader believed that he could have become Kenya's third president.
In what surprised many, Mr Odinga reconciled with retired President Daniel Moi, folding his NDP party in 2002 for KANU.
While in KANU, Mr Odinga became one of the key figures in Moi's succession, with insiders believing that he was up to getting Moi's endorsement.
In his book Soaring Above the Storms of Passion, Mudavadi says Mr Odinga, then Lang'ata MP, was sure of clinching the seat.
“Raila clearly believed that he would be the third President of Kenya. While I have no clear evidence to this effect, I have always believed that Moi had promised him something futuristic,” Mudavadi writes.
"The Raila Odinga star was on a steady rise. He had made the right dial this time and things were looking up," he wrote, describing the opposition leader's prominent role, displacing the hitherto senior officials who had the ear of the president in the government.
However, Moi made another surprise decision, backing a greenhorn, Uhuru Kenyatta as his successor, forcing Mr Odinga out.
Within the same year, Raila joined forces with other opposition figures, endorsing Mwai Kibaki who went on to win 2002 polls.
Mr Odinga came close to winning Presidency in 2007 when he refused to accept Kibaki's victory. He became Prime Minister after an agreement brokered by the international community.