A government minister has quit in protest at Theresa May making the “calamity of a Corbyn government” more likely, by asking him for help to secure a Brexit deal.

Nigel Adams resigned as a Wales minister and a government whip – the first walkout since the prime minister opened crisis talks with the Labour leader.

In a stinging letter, Mr Adams said Ms May faced two “great challenges”, to “deliver the Brexit the people voted for” and to prevent Mr Corbyn entering No 10.

“Sadly, I fear that we are in danger of simultaneously failing in both,” the MP for Selby and Ainsty, in Yorkshire, wrote.

He added: “At cabinet yesterday, there was an opportunity to get on the front foot for once.

“However, by legitimising and turning to Jeremy Corbyn to assist you at this crucial stage, rather than being bold, is a grave error.

Put It To The People march: Best of The Independent’s pictures Show all 24 1 /24 Put It To The People march: Best of The Independent’s pictures Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent Put It To The People march: Best of The Independent’s pictures Put It To The People protest 23 March 2019 Angela Christofilou/The Independent Angela Christofilou/The Independent

“It is clear now that we will end up in a customs union. That is not the Brexit my constituents were promised.”

Earlier, Stephen Barclay, the Brexit secretary, repeated his personal opposition to a customs union – but said there were no “pre-conditions” in the talks with Labour.

Although the prime minister did not say so, in her Tuesday night statement, Mr Corbyn is certain to insist on a customs union as the starting point for any Brexit truce.

No cabinet resignations have followed the marathon seven-and-a-half-hour yesterday, which ended with Ms May making her dramatic request to Labour.

It is expected that the fiercest opponents – defence secretary Gavin Williamson, Liz Truss, the Treasury chief secretary, and Andrea Leadsom, the Commons leader – will wait to see what results.

However, after the Brexit deal was signed with Brussels last November, it was the following day before several ministers walked out of the government.

Meanwhile, Downing Street announced that the prime minister will meet Nicola Sturgeon, the Scotland's first minister, today as well as Mr Corbyn.

Mr Barclay told the Commons Brexit committee that he did not support a customs union, but added: “Ultimately, if that is where the numbers in the House of Commons go, then the government would – in order to bring this to a resolution in the national interest – accept what the House voted for.