London CNN  — 

A senior UK government minister has warned there is a “50-50” chance Brexit won’t happen, if Prime Minister Theresa May’s deal is voted down in Parliament next month.

International Trade Secretary Liam Fox, a prominent Brexit supporter, told the Sunday Times that the only way to be “100% certain” Britain will leave the European Union is if ministers back the deal.

The UK is scheduled to exit the bloc on March 29 next year. But the road to departure has been a bumpy one – with the latest hurdle May’s beleaguered withdrawal agreement, negotiated with the EU last month.

Liam Fox was a prominent supporter of Brexit in the runup to the 2016 referendum.

The deal needs the backing of UK ministers to go ahead, and a vote was due to be held earlier this month.

But just hours before the vote was to happen, May pulled the plug when it became clear she would lose “by a significant margin.”

The crucial vote is now planned for the third week of January. If it fails, Brexit will be thrown into serious doubt, said Fox.

“If we were not to vote for that, I’m not sure I would give it (Brexit) much more than 50-50,” said Fox.

He called on fellow Conservative Party members to back May’s deal, adding that failure to do so would be “incendiary.”

Juncker to UK: ‘Get your act together’

The biggest sticking point among ministers opposed to the deal is the Northern Irish backstop. The backstop is an arrangement designed to ensure there is no return to a “hard border” between Ireland – which will remain part of the EU after Brexit – and Northern Ireland, when the UK leaves the bloc.

After postponing the vote earlier this month, May made a dash to Europe to seek further reassurances from leaders over the backstop – and placate ministers back home.

European Commission President Jean-Claude Juncker also urged the UK to “get your act together” over Brexit, in comments to German newspaper Welt am Sonntag, the UK Press Association reported.

Juncker branded some Britons “entirely unreasonable” for expecting Brussels to put forward a solution, the report said.

If May’s deal is rejected, the country could face several possibilities – from leaving the EU without a deal, to holding a second referendum that could lead to calling Brexit off altogether.

UK’s ‘pay to stay’ tweet shot down

Meanwhile, the Home Office has been heavily criticized for posting a video on Twitter telling EU citizens living in the UK that they will need to apply to a settlement scheme – in some cases including a £65 ($82) fee – if they want to remain in the country after 2020.

Some social media users criticized the cheery tone of the video – posted two days after Christmas – branding it the “pay to stay” policy.

EU nationals who already have indefinite “leave to remain” visas or permanent residency need not pay a fee.

Labour MP Stella Creasy on Twitter blasted the “jolly message this Christmas from govt to say Brexit means we want to charge you to live in the country you have made your home and contributed so much to over decades.”

The satirical Irish Border Twitter account also discovered that the stock images of smiling millennials used in the Home Office campaign had also been used to advertise a bank in Australia and sustainable technology grants in Canada.