The former Foreign Secretary expressed his concern yesterday in The Daily Telegraph. If Mrs May is replaced, Mr Hague suggested it is likely to be by either a hard-line Conservative Eurosceptic or Jeremy Corbyn. In the latter case he argued the UK would no longer be a reliable member of the Western alliance.
Addressing the EU, Mr Hague commented: “If you leave Theresa May to swing, she will probably fall.
“A new British prime minister is either going to be a more hardline Conservative or Jeremy Corbyn, and how are you going to like that?
“With the former you are going to lose the deal anyway, and with the latter the whole Western alliance will be in trouble.”
Mrs May is trying to get assurances from Brussels that the UK won’t be tapped in a customs union ‘backstop’ after Brexit.
According to her deal the UK will automatically fall into a customs union with the EU if a new trading relationship can’t be established during the transition period, currently set at 21 months.
“If you leave Theresa May to swing, she will probably fall (Image: GETTY )
Anti-Brexit protestors outside Parliament (Image: GETTY )
Should this happen, the UK would struggle to sign comprehensive trade agreements with third countries, and would still have to implement a significant proportion of EU regulations whilst having less say over their content.
Controversially, the UK may not be able to leave the customs union backstop, which is designed to avoid a hard Northern Irish border, without the EU’s consent.
Mr Hague argued: “One way or another, the Prime Minister can only avert a final meltdown if the EU decides to give her some meaningful assistance.
“To be useful, such assistance would have to have legal force.”
The House of Commons is due to vote on a series of amendments to the Prime Minister’s Brexit plan later today.
William Hague served as Prime Minister between 2010 and 2014 (Image: GETTY )
Conservative MPs are being told to back an amendment by 1922 Committee chair Sir Graham Brady, which would call for the backstop to be replaced by “alternative arrangements”.
However, key figures within the Eurosceptic European Research Group, which is pushing for a hard Brexit, have deemed the move insufficient and said they won’t support it.
Another amendment has been tabled by Labour MP Yvette Cooper which could see Brexit delayed by nine months, by extending Article 50, if Parliament has not approved an EU exit plan by the end of February.
Speaking to EU leaders Mr Hague warned: “Just think carefully before you tell Theresa May to go away without the concessions she needs.
“One way or another, the consequences will come back to hit you, as well as us.”