Jeremy Corbyn and the Labour Party have been left rattled this week as a division has sprung up in his Parliamentary coalition against austerity over Corbyn’s plans for what critics have called “Labour’s hard, extreme Brexit”.

The Liberal Democrats, whose twelve votes are vitally important to any prospect of defeating the government during this hung Parliament, chose to abstain on Thursday from an anti-austerity amendment, due to the amendment also containing an explicit commitment to Labour’s Brexit plans, which analysts suggest could cost the country 3.5million jobs and £31bn.

Their Deputy Leader, Jo Swinson MP, confirmed this on Twitter.

Abstained on Labour amendment basically praising their whole manifesto, as agree with some of it but not all, esp e.g. not being in Sing Mkt

— Jo Swinson (@joswinson) June 30, 2017

This comes as a blow to Corbyn, whose hard Brexit positioning seems to be putting off parties who would normally vote with Labour on austerity. Indeed, the Liberal Democrat manifesto at the 2017 general election agreed with Labour on a wide range of issues, including ending the public sector pay cap, while going further than it on some – the Lib Dems promised to reverse the welfare cuts of the last Parliament, while Labour did not include such a commitment.

Prominent Labour figures on social media have criticised the Liberal Democrats for their position, but The Torch’s source within the party simply said: “We will not vote for anything that contains a commitment to leaving the single market. It’s as simple as that.”