(CNN) Arron Banks, the backer of the biggest campaign behind Brexit, asked a controversial data firm co-founded by Steve Bannon to draw up plans for raising funds from the United States as early as 2015, newly leaked emails reveal.

Correspondence obtained by CNN, and first reported by Open Democracy , shows that the British businessman was in contact with Cambridge Analytica CEO Alexander Nix in October 2015 after being introduced by US President Donald Trump's former strategist.

In an email on October 24, 2015 to his associate Andy Wigmore, on which Bannon was copied, Banks said he would like Cambridge Analytica to "come up with a strategy for fund raising in the States and engaging companies and special interest groups that might be affected by TTIP," a transatlantic trade deal between the US and EU to which Bannon was hostile. It was subsequently scrapped by Trump.

"It's clear major donors are sitting on the fence but we aim to do something about that," Banks wrote. "Our first and only priority is to win the nomination and be ahead," Banks added, referring to his bid for Leave.EU to become the official campaign for Britain to give notice on its EU membership.

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Banks also wrote in the October 24 email that Cambridge Analytica's fund-raising strategy could target "people with family ties to the UK."

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