Theresa May’s extraordinary statement last night made clear that she is determined to browbeat and bully parliament and the public into accepting her Brexit deal. Every person who considers themselves a progressive should take all available means to oppose it. Its passage would be a calamitous defeat for the left and wider society, depriving EU and UK citizens of long-held rights, reinforcing the EU’s anti-democratic grip on economic policy, and trashing national sovereignty.

The attempt to deliver on the referendum result has imposed extraordinary strains on a Conservative Party that has ruled this country for much of the last 200 years. The Tory Brexiteers dreaming of “an outward-facing, liberal and global Britain” have been sidelined by the Prime Minister, as has the majority of British big business.

Following the lodestar of her entire career, May has chosen to target and attack migrants, prioritising the ending of free movement above all other concerns. Since the EU treats the “four freedoms” of the single market, including free movement, as all-but inviolable, the result has been to impose huge future costs on the UK. Trade with the EU will be far from frictionless, while the continuing need to sign up to some EU rules in turn hampers the ability for Britain to sign its own trade deals with other countries – as Donald Trump’s immediate reaction to the May deal suggested.

But a rare point of harmony between EU and UK governments has been on the continuation of EU State Aid and competition law provisions – even in the event of a “no-deal” Brexit. These significantly restrict the ability of democratic governments to intervene in their economies – potentially even including parts of Labour’s 2017 manifesto. But the restriction is not absolute, and the real question is the degree of interventionist freedom that a domestic government can win. The aim for a future Labour government, in particular, should be to win as much freedom as it can, while recognising that as long as a close, collaborative arrangement with Europe is desired, this will never be absolute.

However, Brussels officials have cited the “threat” of a Jeremy Corbyn government as driving their determination to keep existing restrictions firmly in place. The EU-UK Withdrawal Agreement observes the existing rules, as does the customs union “backstop”, but of more concern is the insistence in the (less-discussed, but ultimately more important) Outline Political Declaration that the UK will build on the “level playing field” of the Withdrawal Agreement. Even worse, the final arbiter on interpretation of those rules will still be the European Court of Justice – only now the UK would have no say over the making of those laws.

More insidiously, the loss of passporting rights for UK financial services, granting them the right to trade in European financial markets, creates another bulwark against a future government of the left. The replacement of passporting with the (less-comprehensive) “equivalence” regime grants financial market access to non-member states only at the EU’s discretion, and this discretion can be removed with just 30 days’ notice. Discussions on “enhanced equivalence” are highly unlikely to alter the fundamentals. For countries with large, internationally-focused financial service sectors, the threat of losing access to their main market abroad creates a gaping economic wound waiting to be poked.

The EU will not hesitate to use the leverage this creates, as Switzerland has recently discovered. Jean-Claude Juncker asked for a “stick” to use against the Swiss government, and control over financial market access has proved perfect in negotiations.

We have seen how a would-be radical government was brought to heel in Greece through an EU institution’s control of its banks. A future Labour government in Britain should not leave itself open to such obvious blackmail. Taken together with the expectation that State Aid and other anti-democratic provisions will remain in place post-Brexit, as overseen by EU institutions, the May deal will prove substantially more restrictive on future governments than existing EU membership.

There should be no debate for the left about any of this. May’s deal is an abomination that, if ever passed, would represent a major defeat for the left, and all those who support an open society in a sovereign country. Remain is unambiguously better than what is on offer: better for democratic rights, better for economic democracy, better for sovereignty. If it takes a second referendum to defeat it, that option should be taken.