With two weeks until the European parliamentary elections on 23 May, pollsters are predicting that no fewer than 30 of the 73 candidates for Nigel Farage’s Brexit party will be elected and so could be taking their seats when the new parliamentary session begins on 2 July. That’s more than is predicted for all the remain-supporting parties put together (excluding Labour, which still says it wants to get a Brexit deal) – which is quite a feat for a man who hasn’t presented a manifesto, disclosed his funders or come up with any details of how a post-Brexit Britain would function.

There is a very simple reason for Farage’s rosy prospects: he is facing no resistance, even though opinion poll after opinion poll shows the remain majority growing by the day. At last week’s local elections, Theresa May and Jeremy Corbyn would have had you believe that people deserted them and voted in record numbers for remain-supporting parties such as the Liberal Democrats and the Greens because they want to leave the EU as soon as possible, no matter how dire the consequences. That verges on open contempt for the electorate, and Trump-like spin. The EU elections provide an opportunity for the people of the United Kingdom to knock some sense into the heads of their political leaders.

With the remain vote in effect divided between up to five parties – Change UK, the Lib Dems, Greens, Plaid Cymru and the SNP – Farage will be able to take victory for granted unless the playing field is levelled out. He and his rightwing backers know only too well that winning a sweep of MEP seats will be interpreted as a mandate for the Brexiteers, as they set about implementing the most extreme political ideology seen in this country in living memory. What is more, it would expand the bloc of rightwing MEPs with divisive and sinister global agendas sitting in the European parliament.

I am therefore attempting to even the playing field by today launching Remain United, a tactical voting and campaigning website to give voters advice on which remain-backing party they would be best off supporting in order to maximise the number of seats these parties capture between them in the forthcoming election. I am a private citizen with no political affiliation – the recommendations Remain United will make are based on robust polling and scientific methodology never before used in an EU election. The aim is to assist pro-EU voters achieve the result they want in electing EU-supporting MEPs.

Importantly, we have treated Labour as a pro-Brexit party. Should Corbyn declare an unambiguous pro-EU position, or show support for a confirmatory referendum in all circumstances, we would be delighted to revise our recommendations.

This tool is needed because the EU elections use a specific proportional representation voting system that requires parties meet regional thresholds in order to win one or more seats. This will split the remain vote. It is therefore critical that voters who want to elect EU-supporting MEPs vote tactically. Unlike in a general election, these elections are not about individual personalities but about giving support to a party.

We need to galvanise the remain vote, energise voters and encourage turnout. In more stable political times, a low turnout in the EU elections was a luxury we could afford. Not this time around. If we are to avoid them turning into a fanfare for Farage, pro-European voters as well as moderate leave voters need to get their heads around tactical voting and encourage others to back a single remain party in their region. We all need to put traditional loyalties and domestic issues to one side, think smart – and not split the vote.

It’s about one issue, and all that will matter is the numbers. I have no doubt that a great many Labour candidates will not be happy with me, and, while I know a lot of them are passionate about remaining in the EU, the simple fact is they are standing for a party that currently wants to get us out. If Labour changes its position on Brexit, Remain United will adjust its recommendations.

All I want is for Remain United to lift the fog so that people who oppose Farage – and his chilling authoritarian vision for our country – can deploy their votes strategically and effectively. The battle ahead is one that we cannot afford to lose.

• Gina Miller is a transparency activist and the founder of Remain United

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• This article was amended on 10 May 2019 to remove an incorrect detail about electoral law.