Mr Farage claims that Britain has a 50/50 chance of leaving the EU. The eurosceptic party leader insisted he would not “desert” Ukip as its annual conference gets under way in Doncaster.
But he said the poll on the UK’s future in the Union would take up all his energy as he described his growing confidence in a so-called Brexit.
Mr Farage said: “I used to think we had 33% chance of winning but now I think it is 50%.”
The Ukip leader insisted the party could hold its head high following the general election and predicted it would do well in next year’s polls in Scotland, Wales and Northern Ireland.
He added: “But that is not where my priorities lie. I am more interested in winning the referendum. I’m not deserting the party but winning the referendum is absolutely key and that’s where our energies must go.”
The conference kicks off with a session on “Europe in crisis” that will focus on migration and calls for borders to be secured.
Earlier this month, Mr Farage launched an independent Ukip campaign for a Brexit amid fears David Cameron will stage a vote next year, but has said he will not seek designation for himself or his party as official leaders of the No campaign.
The party leader has pledged to work with other “no” groups in the run-up to the vote, which will be held before the end of 2017, and “The Know” group – led by Arron Banks, a major Ukip donor – as well as the “for Britain” organisation will appear on the conference stage.
They are expected to announce the creation of a new group called “Leave.EU” that will bring together all the “no” campaigns under one umbrella organisation.
In his keynote speech to activists today, Mr Farage will say: “Ukip can be proud of the four million votes cast for it this year. But that was under first past the post.
“Next year there are proportional elections in Scotland, Wales, Northern Ireland and London where Ukip will make significant inroads and build our elected and electoral presence.
“But above all we are looking forward to the referendum we have fought for for so long.
“Ukip is committed to leaving the EU, and we have always said that we would work with anybody who shared the same aim.”