Once, political parties were meant to solve the voters’ problems. Now it’s the other way round. Voters must be experts in the most arcane details of the d’Hondt system of proportional representation and make predictions that are next to impossible, while receiving no help from the politicians who claim to lead them.

The chaos Brexit has brought has stopped Britain dealing with every real issue, from street crime to climate change. According to the polls, a clear majority of the population now realises Brexit merely worsens old problems, then adds some new ones, just for fun.

You cannot put the Greens as your first preference, Lib Dems second, Change UK third (rearrange according to taste)

In normal circumstances, millions would understand the stakes – feel “the fierce urgency of now”, in Martin Luther King’s words – and vote in the European elections for the opposition party best able to finish off a dying administration and discredited idea. Scottish voters can lend their support to the anti-Brexit Scottish National party and, for this is the crucial point, leave their thoughts about whether Scottish independence is a good idea for another day. Brexit is what matters now. Everything else can wait. The luckless English and the Welsh don’t have this option. The Labour leadership does not oppose Brexit and, in defiance of the wishes of its supporters, is not fighting for the electorate to have the right to approve an exit plan.

The inability of the leading opposition party to oppose extends beyond its sneaky fudges. Labour is no more challenging every half-truth and whole lie made by Nigel Farage than it is exposing the empty nationalism of the seeming limitless supply of Tory leadership candidates. It’s almost as if Jeremy Corbyn and the upper-class Stalinists who surround him are so lost in the infantile leftist belief that the EU is a capitalist and militarist conspiracy, they would rather let the right have its way than reverse Brexit. Without leaders, Labour voters are meant to solve Labour politicians’ problems for them.

Facebook Twitter Pinterest Ponder the positioning of Emily Thornberry, Labour insiders say. Photograph: Mark Thomas/Rex/Shutterstock

Instead of asking for a clear and simple message – “Vote Labour and stop Brexit”, for instance, or even “Vote Labour for a people’s vote” – Labour insiders tell remainers to forget about Corbyn and his clique. We should instead appreciate the subtlety of Keir Starmer’s shimmying, they say, ponder the positioning of Emily Thornberry, and wonder what John McDonnell is thinking, assuming, that is, he thinks at all.

I have had party loyalists tell me in all seriousness to examine the European election candidates’ lists and note that so-and-so standing in London or Yorkshire’s whatshername are good Europeans who deserve a personal vote, however little you think of the party leadership. The question that arises is not so much how many voters will do this, as why the hell should any voter be expected to do this?

In normal times there would be a way out. Remain supporters would realise that Labour does not care about its supporters as long as they carry on voting for it. They would switch to the Liberal Democrats, the Greens, Change UK or, in Wales, Plaid Cymru. As European elections are run on the d’Hondt PR system, surely every remain vote will count.

But we live in abnormal times – or should that be subnormal times? – and there is a snag. De hitch with d’Hondt is that its intricacies penalise smaller parties. You cannot transfer your vote and, for instance, put the Greens as your first preference, Lib Dems second, Change UK third (rearrange according to taste). You must choose one and hope that your fellow remainers make the same choice. To make matters worse, the country is divided into regions of varying size, and the threshold for a seat varies with them. The results can be decidedly skewed. In 2014, the Greens and the Lib Dems won 15% of the vote but only 6% of the seats. The Tories won 17.7% of the vote in the north-east, which was not enough to win one of the seats. If you are a remainer in Newcastle upon Tyne you must decide whether the Lib Dems, Change UK or the Greens provide the banner to rally behind, while all three parties shout as loudly as they can that they, of course, are the winning choice.

Voters should not be asked to make these impossible calculations. The anti-Brexit parties ought to have reached an agreement to not run against each other. The Lib Dems certainly began talks with Change UK – but, strangely, not with the Greens – on forming a popular front against the Brexit right with a clear message: Remain. Chuka Umunna and his colleagues wanted none of it.

Facebook Twitter Pinterest Chuka Umunna, left, and Anna Soubry, two of the MPs behind Change UK. Photograph: Tolga Akmen/AFP/Getty Images

You can see self-interest at work. The European elections are Change UK’s chance to break out and become a national party. It is launching on Tuesday and promising my Westminster colleagues that it will burst on to the scene like a thunderclap and become the natural focus of all who oppose Britain’s humiliation. I can only say that Change UK had better deliver. Otherwise, their determination to establish their “brand” at all costs will be nothing more than an exercise in self-defeating selfishness.

King spoke of “the fierce urgency of now” when he led a march on Washington in 1963 that persuaded a coalition in Congress to give black Americans civil rights. The urgency for unity, despite all other differences, is present in modern Britain. Leave the EU and jobs, living standards and the tax base on which public services rely will suffer – which is why Labour’s doublespeak is so scandalously negligent.

The Greens want international cooperation on climate change; the Lib Dems and, I assume, Change UK, want multinational solutions to common problems – worthy aims both, that will be harder to achieve outside the EU. All want to see off the Brexit charlatans who have so battered this country that we are incapable of thinking honestly about our future. They have a common cause but can’t find a common purpose. No one is asking opposition politicians to provide leadership of the calibre of Martin Luther King. But any kind of leadership, however modest, would provide a long overdue relief.

• Nick Cohen is an Observer columnist