Ukip will this week launch its own campaign for a No vote in the upcoming referendum on Britain's membership of the European Union.
Leader Nigel Farage said he was "ready to work with absolutely anybody" in the battle for withdrawal from the EU.
But he said he would not be signing his party up to either the No campaign set up at Westminster or the Know group launched by Ukip donor Arron Banks and other business figures.
Ukip's drive will kick off on Friday but Farage declined to say who the campaign leader will be.
He told BBC Radio 4's Today programme: "I haven't got a clue at this stage.
"It may well be somebody we haven't even considered, somebody from the world of entertainment or business who has never been in politics at all."
Farage has been described as "too divisive" to lead the official No campaign himself.
The EU referendum is expected to happen at the end of 2017.