The EU elections on Thursday were billed as the vote no one wanted to happen.
But despite Theresa May's best efforts to get her deal through parliament in time to avoid the poll - the vote is now inevitable.
According to a YouGov-European Council on Foreign Relations the Brexit party is set to get twice as many votes as any other party - with 33.4% of votes.
It has the Lib Dems on 17.3%, Labour on 16.1% and 9.2% for the Green party.
The Conservatives are in fifth, on 8.3%.
All major anti-Brexit parties, including Change UK, the Scottish National party and Plaid Cymru, are on 37.5% of voting intentions.
The Brexit Party and Ukip are on 36.1%.
The electoral system for the European elections is the d'Hont method which is a form of proportional representation.
Under the system you vote for a party rather than a candidate.
Remainvoter.com - an independent group of grassroots campaigners - have worked out which party pro-EU voters should opt for in order to maximise the power of their vote.
Any hopes that the pro-Remain parties could work together in a formal capacity were dashed during the Peterborough by-election when they failed to agree on a candidate.
When it comes to the EU elections Vince Cable said he had made overtures to the other parties but "frankly, we didn't get a very warm reception."
The Lib Dem leader said he had approached the Green Party and Change UK to suggest joint candidates.
The Greens say joint lists are not "desirable" and Change UK has said an alliance "wasn't ever on the agenda".
How do the European elections work?
The UK currently has 73 seats in the European Parliament, just under 10% of the 750 who make up the total. There are 70 in Britain and 3 in Northern Ireland.
Unlike in Westminster elections, people don't vote for a single candidate in their constituency.
Instead, the UK is divided into twelve constituencies.
They are the nine English regions, Scotland, Wales and Northern Ireland. Each is given a number of seats based on how many people live there.
MEPs in the UK are elected by a closed proportional list system.
That means the parties submit a list of their candidates for a region, in priority order, and the number of MEPs they see elected is based on the share of the vote they get.
The actual method for counting votes in each region is known as the 'D'Hondt system'.
This mathematical formula is very complicated but here is a basic guide.
In each region, the party with the most votes gets the first seat. Simple.
Then, however, that party's total vote figure is divided by two - and the party with the most votes in the second round (after that division) gets the second seat.
The process is repeated via a formula until all seats have been dished out.
As it goes on, if a party wins a second seat in its region, its vote total is then divided by three. If it wins a third seat, its vote total is then divided by four. And so on.
If you're into this sort of thing there's a full explainer here.
Regions and the number of MEPs they elect
East Midlands - 5
East of England - 7
London - 8
North East England - 3
North West England - 8
South East England - 10
South West England (and Gibraltar) - 6
West Midlands - 7
Scotland - 6
Yorkshire and the Humber - 6
Wales - 4
Northern Ireland - 3
East Midlands - Vote Green
Current polling predicts: 1 Remainer party will win 1 seat
Tactical voting indicates: A further seat can be gained for a second pro-European party
The Lib Dems look secure in winning a single seat.
The next best placed pro-European to win is the Greens.
A Green gain will displace a pro-Brexit party, and lock them out of the East Midlands.
Eastern England - Vote Green
Current Polling predicts: 1 Remainer seat
Tactical voting indicates: A further seat can be gained for a second pro-European party.
The Liberal Democrats look secure in this region, but the Greens are fighting for last seat against the Brexit Party.
RemainVoter.com recommends voting Green to secure a further Remainer.
London - Vote Change UK
Esther McVey claims she's 'on the side' of working class in brazen Tory leader bid
Current Polling predicts: 3 Remainer seats across two parties.
Tactical Voting indicates: Possibility for a 4th seat for a third pro-European party.
Lib Dem and Green seats look secure, so RemainVoter.com recommends vote Change UK to gain a 4th Remain seat in London.
Former journalist Gavin Esler is standing for Change UK in London.
North East - Vote Liberal Democrat
Current Polling predicts: 0 Remain seats
Tactical Voting indicates: 1 Remain seat possible
With only 3 seats, the only way a Remainer can get elected is if pro-EU voters opt for the Liberal Democrats.
Even if it doesn't result in a Lib Dem
To bring a single seat within reach of a Remain party, RemainVoter.com recommends voting Liberal Democrat, and bring a friend. This will increase the key indicator of national vote share for Remain parties: don't give up, instead get out and vote.
North West - Vote Green
Current Polling predicts: 1 Remainer seat is secure.
Tactical Voting indicates: 1 more Remain seat can be added
The campaign group has the Lib Dems on course to win one seat and they say that just a small number of switchers from Labour and Change UK voters to Green will give Remainers an extra seat.
They would join 3 sitting Lab MEPs who are expected to keep their seats.
Far-right extremist Tommy Robinson, who is an advisor to Ukip leader Gerard Batten, is barred from joining the party, and will stand in the North West region as an independent.
The head of Labour's campaign group Laura Parker is third on the party's list in London but Remainer.com does not advocate backing the party because of its
Northern Ireland - Vote your preference: Alliance; SDLP; Green; Sinn Fein*
1. Alliance
2. SDLP
3. Green Party Northern Ireland
4. Sinn Fein
These are the Remain parties in Northern Ireland Remainvoter.com recommends voting for them in this order.
This is because the voting system is different in Northern Ireland which has the Single Transferable Vote.
The site tells voters to vote for all the parties they feel they can support.
Brexit: Theresa May begs hostile MPs to BACK deal - and get a second referendum
Scotland - Vote Liberal Democrats to win 2 Remain seats
Current polling predicts: 3 Remain seats
Tactical Voting indicates: 5 Remain seats
Recent polling shows SNP confidently gaining 3 seats with undecided Labour voters blocking a 4th.
RemainVoter.com says their modelling shows LDs have the momentum to win a seat while helping the SNP win the 4th seat.
South East - Vote Change UK
Current Polling predicts: 3 Remainer seats for 2 pro-EU parties
Smart Voting indicates: We can gain a further seat for a third pro-EU party
The Liberal Democrats look secure on 2 seats and the Greens on 1 seat. Neither will get another, so vote Change UK to get a 4th Remainer seat in the Southeast.
Brexiteer-in-chief Nigel Farage himself is standing in for re-election in the south east.
South West - Vote Green
Current Polling predicts: 1 Remainer seat is secure
Tactical Voting indicates: We can gain 1 more Remainer MEP
Change UK's Rachel Johnson may be the big name on the ticket but Remainers should vote Green instead according to Remainvoter.com.
The Liberal Democrats are on course to win one seat so Remainer.com encourages voters to go for the Greens to get a second Remain seat in the South West.
This would return Green MEP Molly Scott Cato to Brussels.
Wales - Vote Liberal Democrats
Current Polling predicts: 1 Remainer seat is secure
Tactical Voting indicates: 1 more Remain seat can be added
Plaid Cymru is set to win one seat in Wales. With smart voting, the Liberal Democrats can win also win a seat without encroaching on Plaid Cymru. That gain will mean half the MEPs in Wales are outright Remain supporters.
West Midlands - Vote Green
Current Polling predicts: 1 Remainer seat is secure
Tactical Voting indicates: 1 more Remain seat can be added
It looks like the Liberal Democrats will win one seat.
With Remainers voting Green, we can add a second Remain supporting MEP in the West Midlands, with Labour losing out because of its lack of commitment to their majority Remain membership.
Yorkshire and the Humber - Vote Green
Current Polling predicts: 1 Remainer seat is secure.
Tactical Voting indicates: 1 more Remain seat can be added
The Liberal Democrats are set to win a seat. If enough people vote Green, they too will win a seat.
The widely-loved former Lord Mayor of Sheffield - a former refugee who became mayor at 29 - is top of the Green Party's list for Yorkshire and the Humber.
He recruited poets and musicians to perform at council meetings and famously "banned" Donald Trump from the city.
The region doesn't currently have a Green MEP but the party won almost 8% of the regional vote last time.
You can see the full list on the Remainvoter.com website.
What the parties say
Change UK MP Sarah Wollaston told Westminster Hour tactical voting could be used to “maximise the total unequivocal Remain vote”.
She told Carolyn Quinn: “People are making calculations about how to vote tactically and that can then juts become a rolling process and self-fulfilling prophecy. But there is a point here that we’re trying to maximise the total unequivocal Remain vote as well as maximise the number of MEPs.
“If you look at some of these tactical voting sites, in London and the South East for example, the tactical voting site Remain Voter is actually advising people to vote for Change UK because it’s about the marginal gains.
"So it’s not necessarily about voting for the most popular lead candidate, it’s about saying where could you put your vote where you actually would deliver at the margins an extra MEP.
"So there are parts of the country where that might be for us and there are parts of the country where it might be for Green or for Lib Dem. These sites exist and people will make their own judgements.”
