The Kenyan midfielder has been a target for a number of Premier League clubs this summer and the Bluebirds are expected to make an official bid soon along with Southampton according to Hoops manager Neil Lennon.
"There are a couple of clubs still in the mix but nothing has been done yet. Cardiff are in but they've not made a concrete offer," he said.
"I'm not convinced the terms of the offer they're looking at is what we want.
"They're going to come again, I think, but as things stand he's our player.
"We'll see him when he joins up with us and take it from there. We accepted one bid previously and that's the level we're looking at.
"Southampton may come back so I wouldn't rule them out."