The Azimio La Umoja camp, led by leader Raila Odinga, held a meeting Wednesday with its elected legislators to chart its way forward after rival William Ruto was named President-elect.
Mr Odinga, his running mate Martha Karua and Wiper leader Kalonzo Musyoka met with elected MPs, governors and other legislators allied to Azimio at KICC, Nairobi.
"Ours is victory deferred but it's coming home," said Ms Karua.
"Our figures show that we command the National Assembly."
Mr Odinga previously signalled a Supreme Court battle to determine the legality of the outcome of the presidential vote after he rejected the results.
At the same time, Dr Ruto also met with elected Kenya Kwanza at his official Karen residence. He announced that 10 newly elected independent MPs have joined his coalition.