“Keep the faith in our party. We are going places,” said Ukip leader Paul Nuttall as he launched the party’s local election campaign in a Margate hotel on Wednesday. But which places is Ukip going to? Conservative and Labour politicians, and some commentators, continue to obsess about the Ukip threat. Yet the real-world evidence increasingly suggests something different – that Ukip is a party in crisis, losing support, losing elections and losing prominent voices.

True, in spite of its rivals’ policy triangulations, Ukip still scores around 11% in most national opinion polls. That means it is still a factor in most calculations, especially in England and Wales. But for how much longer? Ukip’s recent electoral record is poor. Mr Nuttall failed to win the Stoke Central byelection where he had high hopes. Few think Ukip will do well in Manchester Gorton next month. The party has also been losing English council seats in byelections to all-comers in many regions – one in Aylesbury last week, another in Tendring in Essex. Ukip’s only MP, Douglas Carswell (whose seat includes the Tendring ward), has resigned, as has his fellow former parliamentary defector, Mark Reckless, now in the Welsh Assembly. Diane James, who led Ukip for 18 days last year, is considering joining the Conservatives. Big ego donor Arron Banks has left the party.

There seems precious little chance of a Ukip uptick any time soon. In the local elections, the party is only contesting 48% of the seats; four years ago it was contesting 73% of them. Election experts predict heavy losses in May – as many as 100 of the 146 seats they are defending. Right now, the idea that scores of MPs are vulnerable to a Ukip surge, which seemed a potent possibility two years ago, appears increasingly improbable. Insiders predict a Ukip general election share of 5% or 6 % in 2020, perhaps followed by disintegration.

Mr Carswell said this week that Ukip should disband, because its mission of getting the UK out of Europe has been accomplished. That’s unlikely. But Ukip’s best days may be behind it. The three-year period in which Messrs Carswell and Reckless appeared to be the outriders of a lurch of Tory MPs and voters to Ukip has passed. But the events of those years were volcanic. They helped push Europe to the top of the Tory agenda and to ensure the eventual triumph of the anti-EU cause. What is Ukip’s purpose now?

Winston Churchill, who moved from the Tories to the Liberals and then back again, once observed that while it was relatively easy to rat in politics, it was harder to re-rat. This was not true of Mr Carswell and Mr Reckless, who were never really ideologically mainstream members of Ukip. Their politics were primarily libertarian and anti-state. The intensity of their anti-EU feelings owed more to dislike of government and bureaucracy than of migrants. This set them at one remove from Nigel Farage and the Ukip mainstream. The reality is that neither of them had reason to stay in Ukip after the vote to leave Europe went their way.

The larger question now is whether Ukip is finished as a major force. If it is, the re-ratting of Mr Carswell and Mr Reckless (neither of whom has yet formally rejoined the Tory party) is not the cause but a symptom. Ukip has yet to rediscover a political purpose following the referendum. Hence the current losses and the diminished profile. With no MP to Ukip’s name, even the BBC’s Question Time may have quietly decided it is not obliged to feature a Ukip voice so often.

Those who say Ukip still matters point to the fear it exerts in other parties. But that may be changing. The re-ratters can’t be certain of a warm embrace in Mrs May’s party, which for all its concessions to the Brexit right says it prefers to cultivate the centre ground and even shows some signs of softening its Brexit goals. Meanwhile Labour seems to have remembered that most of its most loyal voters are remain supporters who welcome controlled immigration. The danger for Labour in May could be the Liberal Democrats, rather than Ukip.

Ukip risks evolving into a more purely anti-immigrant party, especially if Mr Farage continues to play a part in it. That possibility should not be dismissed, nor the impact it may have. Similar parties play important roles in most European countries and may even win the French presidency. There is no cause for complacency. But British voters have mostly spurned such parties over the years. It is to be hoped that such good sense continues. If it does, Ukip will have helped to make history only to discover that it now risks becoming part of it.