When Theresa May called the snap general election a few short weeks ago, it was on the assumption of a landslide Tory victory, consolidating her power-base in parliament and driving through extreme Brexit without opposition.

In order to try and mitigate the damage to our country, on the day the election was called, Best for Britain launched a crowdfunder for a tactical voting campaign. Our tactical voting dashboard makes recommendations on the best candidates to stand against extreme Brexit by limiting a Conservative majority in 573 constituencies around the country.

Polls in the past week have been mixed, with everything from a hung parliament to a Conservative landslide predicted.

As Peter Kellner, the former YouGov pollster, has explained, the key difference between the polls forecasting everything from a hung Parliament to big Tory majority is not the expectations of how people will vote, but who will turn out to vote.

The polls predicting a big Tory win assume that many of the young people who have registered won't show up on the day. Those who see a much closer outcome assume most of those who have registered will vote.

It turned out to be the rift choice to go out immediately after Theresa May called the election: the massive response showed that there is a large part of the population who are gravely worried about the reckless approach the Conservatives are taking on a range of issues, including Brexit.

We've identified the best call for a tactical vote across 573 constituencies, and identified a series of "champions" who we've given support - in some cases with campaign donations, some with social media marketing and targeted advertising.

Our main concern is making sure we have independent-minded MPs in parliament who will scrutinise and challenge the Brexit process at every turn. On 19 June, the most important negotiation in a generation begins and our MPs from all parties and citizens across the country have a stake in what happens next- and they need to be part of the process.

Theresa May's performance during this election campaign will hardly fill anyone with confidence about her diplomatic skills, and we deserve better than a rubberstamp parliament waving through whatever deal - or lack of - the prime minister comes up with.

The future of education, the NHS, social care and job opportunities in Britain will be hugely affected by the outcome of the negotiations with the EU. Even Jeremy Hunt thinks that the Tories' NHS pledges might not be fulfilled because 'Brexit could go wrong'.

It's clear there is little enthusiasm for Theresa May's approach to Brexit across the spectrum: the Financial Times half-heartedly endorsed May's Conservatives, but damningly concluded that "her ability to deliver the best deal for Britain in terms of the closest possible relationship with the EU is worryingly unclear."

The Observer has been equally forthright, suggesting that the Conservative campaign showed that May is "undeserving" of the support of the nation as she heads into Brexit negotiations with her "disastrous mantra that no deal is better than a bad deal", and urged its readers to vote tactically "in whatever way best limits the worst impacts of Brexit on Britain's future".

Theresa May
2 June 2017: Prime Minister Theresa May reacts during a campaign stop near Doncaster Scott Heppell/Reuters

Yet despite the calamities on the campaign trail, it seems quite possible that Theresa May will increase her parliamentary majority. The Conservative right and borderline Ukippers, not sated by the the Brexit vote, will see an increased Tory majority as a mandate for further isolationism and harder borders. No doubt they will see recent terror attacks as strengthening their case, and exploit them accordingly.

Brexit is the most important issue facing the country: the future of our economy, our security and our welfare all depend on how the negotiations with Europe proceed. Theresa May's behind-closed-doors, deal-or-no-deal approach is ill-conceived and bound to fail.

This Thursday, a large-scale tactical vote to limit a Conservative majority is the best hope Britain has: that's what we're aiming to do at Best for Britain.

Eloise Todd is the CEO of the Best for Britain campaign group.