The Sh200 billion coal fired power plant is being forced on Lamu people, Wiper leader Kalonzo Musyoka said.
Mr Musyoka said the plant had hazardous effects on the environment and human health.
Speaking at a rally in Kizingitini Island in Lamu East during his tour of the area, the Nasa co-principal lauded Wiper deputy party leader and county woman representative Shakila Abdalla for opposing the project.
Mr Musyoka said Lamu people should rise up and denounce the project.
He said a similar project was rejected in Kitui for the same reasons despite the area being rich in coal deposits.
Ms Abdalla said she will not be deterred in her decision to oppose the coal plant.
She said certain individuals “have been pocketed” to accept the coal project.
“I will not relent. I will fight for the people of Lamu on the coal power plant,” she said.
Mr Musyoka called on the people of Lamu to join hands with the rest of Nasa supporters across the country and vote out the Jubilee government in the coming elections.
Wiper secretary-general and Mombasa senator Hassan Omar said Mr Kalonzo should be the Nasa flag-bearer.
“At Wiper, we have already proved that Kalonzo is a good leader. He has elected me as the party secretary-general and Ms Abdalla as his deputy,” Mr Omar said.
This is Mr Musyoka’s first visit to Lamu since 2013. During the tour, Mr Kalonzo was also accompanied by Wiper aspirants countrywide.
Lamu has previously been perceived an Opposition stronghold having voted for ODM in the 2013 election.
But analysts say the tide has changed and it will be a struggle for the Opposition this time round.