Mr Farage told BBC One’s Sunday Politics programme, “New UKIP is a lot more professional, a lot more smiley, a lot less angry, and it’s going places.”
If the party did not win any seats at the next general election and Labour took office without promising an in/out EU referendum he would resign, he said.
He said, “I will have failed. I will have spent years trying to achieve this goal.”
UKIP advocates withdrawing from the EU and has been involved in growing arguments about the issue ahead of European elections in May.
Mr Farage continued, “I got into politics, not because I wanted a career in politics. Far from it. I did it because I genuinely don’t think that this European entanglement is right for our country.
“A lot of people have now woken up to the idea that we’ve lost control of our borders; it’s costing us money. Now is the time, now is the moment for UKIP to achieve what it set out to do. And I think we’re going to do it.”
If he did resign after the general election the party would not founder, he predicted.
He said, “Everybody says it is a one-man band, but it is far from that. Reforms I have made to the party, by getting rid of old UKIP, were making it stronger politically.”
In January, Mr Farage decried “Walter Mittys” in his party’s ranks after suspending Oxfordshire councillor David Silvester, who had argued that changing the law to allow gay people to marry was the cause of flooding. Last autumn, MEP Godfrey Bloom was ejected from the party after using the phrase “bongo bongo land” and joking that some female UKIP activists were “sluts.”
And aspiring UKIP candidates now have to declare that they have “never engaged in, advocated or condoned racist, violent, criminal or anti democratic activity” and that there are no “‘skeletons in my cupboard’ that may cause me or UKIP embarrassment”.
The party’s immediate target is now the European elections. Mr Farage suggested that Labour leader Ed Miliband had made an error by pledging to hold an in/out referendum on UK membership of the EU only if a further transfer of power from Westminster to Brussels was on the table. In practice, this would mean that an EU referendum in the next parliament was unlikely, Mr Miliband has said.
Mr Farage said, “What the Labour Party has done this week with Miliband’s speech is to open up a huge flank to us, and that’s what we’re going to go for. It is wrong to believe that UKIP took votes only from the Conservatives. Most of our voters are coming to us from Labour, some from the Lib Dems, and a lot are non-voters. Two thirds of our voters would never vote Conservative anyway.”
Prime Minister David Cameron has also criticised Labour’s EU strategy, calling it “a policy clearly designed by a committee who couldn’t agree what to do.”