Ukip's deputy chairman Suzanne Evans has effectively been sacked as a party spokeswoman after saying leader Nigel Farage was perceived as "very divisive".
She said Mr Farage should not lead the campaign to leave the European Union ahead of the referendum promised by the end of 2017 because of the way he was viewed.
A leaked internal Ukip email following the comments revealed that Mr Farage had decided she should be frozen out, with press officers instructed not to have any further contact with her.
In an interview with BBC2's Daily Politics, Ms Evans said: "I think Nigel is a very divisive character in terms of the way he is perceived.
"He's not divisive as a person but the way he is perceived is as having very strong views that divide people."
She suggested that some form of "joint leadership" may be the best way to approach the campaign.
"Why should one person front it? Why shouldn't it be Nigel alongside someone from the Labour party, from the Conservative party and perhaps from business as well? That I think would be much more convincing."
An internal email obtained by the BBC showed the Ukip leadership took swift action against Ms Evans.
The sender of the message, who was not identified, wrote that they were issuing a "directive" having "just spoken to Nigel".
"From this moment onwards no-one employed by the Ukip press office is to have any further contact with SE," the email said.
The message stated that no interview bids were to be accepted and "she is not to be offered as an official Ukip spokesman".
It added that "no-one is to brief SE or advise her on any issue".
Mr Farage had recommended that Ms Evans should lead the party when he quit from the post after failing to win the Thanet South seat at the general election, only to have his resignation refused by Ukip's national executive committee.
Last month, during a round of infighting at the top of Ukip following the announcement that Mr Farage would continue, her role as policy chief ended when her contract expired.
Mr Farage has said he is "prepared" to lead the No campaign in the EU referendum – but suspects the role will go to a figure from "outside normal politics".
He has raised the prospect of an apolitical figure – such as entrepreneur James Dyson – spearheading the campaign.