On June 16, Nigel Farage, the leader of the UK Independence Party (UKIP), unveiled the party's latest campaign poster. It showed dark-skinned migrants queuing up, with the caption "Breaking point: how the EU has failed us all." For many, this was a step too far, clear evidence of the party's racialized politics.

For two decades, the lurid yellow and purple of the UKIP logo has become an increasingly common sight in Britain; on billboards, buses, and out on the campaign trail. The party's campaigns have often descended into farce: the festival in Croydon, aimed at fostering links with ethnic minority communities, where the steel band refused to play when they realized who they had been booked by, the flotilla of fishing trawlers outside Parliament that ended with Farage and Bob Geldof shouting at each other from different boats.

UKIP has often been dismissed - memorably, David Cameron said its members were "fruitcakes, loonies, and closet racists, mostly" back in 2006 when he was the newly elected Conservative leader. Little did he know at that point that a decade later, one of the defining moments of his premiership would be holding a referendum on EU membership - the very thing demanded by UKIP for years. This is a critical point for Britain, but also for UKIP.

"Should the electorate vote for EU withdrawal, UKIP would be deprived of its original raison d'être," says George Eaton, political editor of the New Statesman. What happens next to the party that has, against everyone's expectations, somehow managed to orchestrate a major turning point for the UK?

Humble beginnings

UKIP was founded in 1991 by the historian Alan Sked as the Anti-Federalist League, a single-issue party dedicated to Euroscepticism. It was renamed UKIP in 1993, adopting a wider right-wing platform and gradually increasing its support base. Its message - that Britain would be better off outside the EU - was easy to understand, but it also meant that it continued to be seen as a single-issue party.

Farage was a founding member. He took over as leader in 2006 and set about broadening the party's appeal, arguing that leaving the EU would be the answer to a whole host of issues, including immigration controls. UKIP successfully harnessed the anti-establishment, anti-politics vote, and made significant electoral breakthroughs in both the 2013 local elections and the 2014 European elections.

In the 2015 general election, the party gained the third-largest share of the vote, ahead of the Liberal Democrats, though this only translated into one seat in the House of Commons. In 2014 high-profile defections from the Conservative Party's Eurosceptic wing - Mark Reckless and Douglas Carswell - gave the party a major boost.

Senior members of UKIP are already planning what comes after the referendum. In a recent interview with the Guardian, Farage suggested that a large number of Conservatives might defect to the party in the event of a "remain" vote, out of anger that Cameron's government opted to support the "remain" campaign.

"The doomsday scenario for these guys is that we lose the referendum 52/48, that I'm seen to have played a big role in the referendum, that a third of the Tory party are irreconcilable with dodgy Dave, because they think he's pulled every trick in the book, he hasn't played with a straight bat, and a third of the Conservative party come and join me and UKIP. That is their doomsday scenario. Anything is better than that."

What next?

The polls are currently so close that it is impossible to say which side will triumph on June 23. "My expectation would be that UKIP will in case of Brexit become a fairly unimportant as a political force. They will then have achieved what they wanted," says Fabian Zuleeg, chief executive of the European Policy Center. "In some ways you might argue it is in Nigel Farage's best interest if there is a 'remain' vote. People might decide - especially those 45 percent which would have voted to leave - that they give their vote to UKIP," he told DW.

Despite its electoral gains in recent years, however, the party is not on stable ground. "Mainstream UKIP is a strange beast at the moment - the party is underfunded," says Jim Waterson, political editor of Buzzfeed UK. "Its entire purpose for 20 years has been this event. If UKIP say the public want to leave the EU, and they get their shot at it and that doesn't happen, then what is its purpose? It starts to look a bit more like an anti-immigration party," he told DW.

Sources in UKIP say that in the event of a "remain" vote, they will take inspiration from the Scottish National Party, which lost the referendum on Scottish independence in 2014, but went on to force a complete realignment of Scottish politics in the 2015 general election.

There is, however, the question of identity. "What UKIP is now trying to straddle is on the one hand being anti-establishment but on the other hand campaigning with a lot of people on the establishment side. That is a very difficult one to square," says Zuleeg. "It's difficult to argue you are the anti-establishment voice when you are clearly part of the political game in a very traditional way."

Whatever happens on Thursday, UKIP clearly does not plan to disappear. "Arron Banks, UKIP's major donor, and Farage are quite openly talking about what they'll do after the referendum in terms of starting a new UKIP-esque movement out of the existing party and what form that'll take," says Waterson.

It seems that we have not seen the last of those yellow and purple logos after all.