Amani National Congress leader Musalia Mudavadi has assured Kenyans the National Super Alliance will not let them down after the August polls.
Mudavadi said the alliance aims at transforming the country and uplifting the livelihoods of Kenyans by fighting vices like corruption.
"United we stand divided we fall," he said at the Bomas of Kenya, Nairobi where key opposition leaders met to cement the formation of NASA.
"Under NASA we will unite Kenyans and put Kenya and Kenyans first for progress prosperity and the dignity of the citizens of this country and that includes you and I."
Opposition leaders Raila Odinga, Kalonzo Musyoka, Moses Wetangula and Mr Mudavadi had met to finalize the formation of the alliance."
The alliance will select one candidate who will take on President Uhuru Kenyatta during the August general elections.