The events of the last few weeks and months have put a spring in the step of those who want a hard Brexit that would wrench Britain out of many areas of European co-operation that have benefited our country. From the defeat of every single amendment to the Article 50 legislation - even widely supported clauses protecting the rights of EU citizens in our country - to Theresa May's threat to take Britain out of Europe without any deal whatsoever, ideological Brexiteers and their cheerleaders in much of the press are feeling triumphalist.
It is time for pro-Europeans to unite, make the positive case for a Britain that engages with Europe to enhance our prosperity and security, and to warn about the danger of the Government's trajectory, while respecting the result of the referendum on June 23rd. That is the argument Tony Blair will make in today's keynote speech for Open Britain this morning.
Tony Blair will say "the people voted without knowledge of the true terms of Brexit. As these terms become clear, it is their right to change their mind." This is common sense logic. An extreme, destructive Brexit was not on the ballot paper, and the voters should have the right to judge the final deal if that is what is on offer.
The Government have said they will deliver the "exact same benefits" outside the single market as we have within it. We all want them to be successful. However, if they do not deliver and negotiate a trade deal that would cause economic pain, people should be able to judge if that is in their personal interest and the national interest. Open Britain believes all options to be on the table because accepting the referendum result, as we do, is not the same thing as accepting the outcome of every political choice subsequently made.
As Tony Blair will argue, the Government have moved beyond hard Brexit to Brexit At Any Cost. We must expose the actual cost of this approach, which in turn will show that the campaign to Leave, and the decision to Leave, was largely based on imperfect information.
The Government's choice to abandon our membership of the Customs Union and the Single Market - our biggest single customer which buys 45% of our exports and supports as many as three million jobs - forces them to voluntarily pursue a trading arrangement that will almost certainly erect greater barriers to trade than we enjoy today.
Their other decision has been to raise the spectre of the harshest Brexit of all, where the UK crashes out of the EU without any deal at all - and without either Parliament or the people having been consulted. This would be unacceptable. We would have no preferential agreement on trade with our largest trading partner, leading to eye-watering tariffs on goods and our being completely outside of the EU's regulatory framework, which would be devastating for the service sectors that make up 80% of our economy. The consequences would, as the Chancellor himself has said, be "catastrophic." This is not inevitable. If it happens, it will be the result of the Government choosing a path they know will inflict economic pain.
Should this happen, Parliament must force the Prime Minister back to the negotiating table to achieve a better deal for Britain; and if she cannot, it is more important than ever that the public be consulted before the Government takes our economy off a cliff-edge.
Open Britain has led the argument against a hard, destructive Brexit. The Government has chosen a path that risks not only our economy but the integrity of the United Kingdom. We don't know if we can succeed in persuading people of the folly of this until it is too late, but, as Tony Blair will say, we will suffer a damning judgement from future generations if we do not try.
We agree with Tony Blair's call to action, which says that pro-Europeans have no option but to come together and make our argument passionately and vociferously. On the economy, we must keep fighting for the best possible deal, which, at the very least, should ensure the Government delivers on their promise of getting "exact same benefits" as our current arrangements.
It is vital that existing, superior trading arrangements are not immediately jettisoned forever if the final deal falls far short. The way to secure that is to ensure that democratic consent is given to whatever the future UK-EU relationship is. The Government cannot have a blank cheque for a hard Brexit. If the deal is not good enough, Parliament should be able to send the Government back to the negotiating table. We cannot be offered an ultimatum at the end of the Article 50 process between a bad deal and no deal. The country should be entitled, in some form, to make a real judgement about the deal on offer.
As a former Prime Minister who served for three terms and gave our country a leadership role in Europe, Tony Blair's views surely have a right to be heard.
It will be an uphill struggle, given the current state of play in British politics, but this is an argument that can be won.