Cord leader Raila Odinga said he would not allow anyone to steal votes in the 2017 elections.
He said all loopholes would be sealed.
He said 2017 would be different from past elections "where certain quarters always found ways to clinch the presidency unfairly".
The Orange Democratic Movement leader assured his supporters that he would never give up attempts to become Kenya's fifth head of state.
"We are marching forward as one as we get to the most important part of this fight for the liberation of Kenyans," he said in Homa Bay Town on Thursday.
"Our is like Nigeria where citizens said they would vote anyone but (Goodluck) Jonathan. We have also said that Kenyans must think of electing anyone but Jubilee."
Mr Odinga asked Cord supporters to take seriously the voter registration from February 15 to March 15.
"When I went to Mombasa, the message was that we must make a difference this time. The weapon for this war is you coming out to register in large numbers so that Nyanza alone produces a million more votes," he said.
The opposition chief also warned leaders in ODM strongholds against "fighting over small seats".
Mr Odinga reconciled Homa Bay Woman Rep Gladys Wanga and Homa Bay Town MP Peter Kaluma. He asked them to concentrate on voter registration.
ODM leaders said the outcome of the investigation on Justice Philip Tunoi would shape the destiny of Kenya.
Mbita MP Millie Odhiambo said should Justice Tunoi be found guilty of corruption, all Supreme Court judges should be sent packing.
Mr Kaluma was pronounced organising Secretary of the branch while Kabondo Kasipul MP Oyugi Magwanga was declared secretary.
Governor Cyprian Awiti said the ODM leader's word was final.