European Research Group warns it will vote against UK-EU deal if sovereignty is not preserved

Jacob Rees-Mogg at the annual Conservative Party Conference - Jeff J Mitchell /Getty Images Europe 
Jacob Rees-Mogg at the annual Conservative Party Conference - Jeff J Mitchell /Getty Images Europe

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The European Research Group (ERG) of Conservative MPs – which did so much last year to oppose Theresa May's Brexit deal and so ushered in the premiership of Boris Johnson – has maintained a Trappist vow of silence while the Brexit talks have been ongoing.

The only eruption was over the Internal Markets Bill, which breaks the law in a "specific and limited way" if a trade agreement is not agreed with the European Union by the end of next month.

I texted several well-known members of the group last night to ask what the ERG was planning next. If I had done that 18 months ago, my phone would have been pinging with splenetic invective about Mrs May's handling of the Brexit talks. But this time – not a peep.

Then a source got in touch. The truth is that the ERG is biding its time as they know there will almost certainly have to be a vote on the new deal before it comes into force, they said.

Ministers can ratify any UK-EU treaty (which is what the final agreement would be) under the Constitutional Reform and Governance Act 2010 (CRAG), which requires it to be laid before Parliament. It then automatically becomes law if MPs don’t vote against it within 21 days of the date of laying.

However, the Government is under no obligation to call a vote on any treaty – it removed its previous commitment to hold a vote on the final UK-EU treaty from the European Union (Withdrawal Agreement) Act 2020, which was passed in January.

But the Government will almost certainly have to pass primary legislation to implement the resulting UK-EU treaty into domestic UK law.

This would need to pass through both Houses before December 31. And, this is where it could get difficult for the PM. One Tory source told me: "For Brexiteers, the overwhelmingly important issue is UK sovereignty.

"If that is not preserved in the final agreement, I have no doubt we will vote against the treaty in whatever vote is called – either under CRAG (if there is one) or for the final domestic implementing legislation."

Another source added: "Our side has made it clear we trust the PM on his red lines like sovereignty etc. Nevertheless, as a research group, we will read it before deciding. In the unlikely event it does not respect sovereignty MPs would vote against."

That could leave Mr Johnson in the invidious position of pushing through his Brexit deal on the back of Labour votes (party leader Sir Keir Starmer told me on my Chopper's Politics podcast earlier this year that he would back a deal – perhaps, any deal – to take the UK out of the EU).

EU President Ursula von der Leyen said on Wednesday that Brussels is looking at "creative" ways to seal the deal. But if this "creativity" means that Eurosceptics will view the deal as "BRINO" – ERG code for "Brexit In Name Only" – then the Prime Minister might be seeing more of his young son Wilfred than he currently already does.

One Eurosceptic source told me: "If a large body of Tory MPs branded it BRINO and voted against the Tory party [then] Boris is toast. They know that and so presumably will avoid it."

It is not just Brexit that is at stake, but conceivably Mr Johnson's entire premiership. After all, remember what happened to Mrs May.

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