As we explained a short time ago, the executive - top tier - of the 1922 Committee will meet the chief whip - the cabinet member in charge of party discipline.

Tory MP and prominent Brexiteer Mark Francois, leaving the meeting of the 1922 Committee earlier, said: "If I were a betting man, I'd bet £50 for Help for Heroes that the second reading of the Withdrawal Agreement Bill will never ever happen and I invite another colleague, whoever it may be, to take my bet."

Radio 4 PM

Image source, UK Parliament

Pro-EU Conservative MP Ken Clarke says "it doesn't reflect well on Parliament that we are unable to get out of the deadlock."

"Whoever is elected, from whatever wing of the party he or she comes, will face exactly the same set of problems," he says.

"I'm not sure any of them [the leadership candidates] have any clear idea what their solution would be."

Radio 4 PM

"Sadly it has become clear that the hill is too high for the hiker," Conservative MP Tom Tugendhat tells the PM programme on BBC Radio 4.

He says the PM should start a leadership campaign now and be ready to step aside as soon as a new leader has been elected.

"I can't praise her enough for having tried so hard," he adds describing her as "a formidable campaigner".

Iain Watson
Political correspondent

The full 1922 Committee meeting of backbench Conservatives has broken up without agreeing a rule change on a leadership challenge.

The group's executive will meet Chief Whip Julian Smith at 17:30.

After that the 1922 will meet again at 18:00.

Image source, EPA

Today's flurry of Westminster activity has been prompted by Theresa May's speech setting out what would be in the Withdrawal Agreement Bill - the legislation required to bring her Brexit deal into UK law.

What did she actually offer? Here are the key points:

• A guarantee of a Commons vote on whether to hold another referendum on the government's Brexit deal
• A vote on different customs options, including a government proposal for a temporary customs union for goods - what Mrs May called a "customs compromise"
• A legal obligation for the UK to "seek to conclude alternative arrangements" to replace the Northern Ireland backstop by the end of 2020
• If the backstop does come into force, the bill would guarantee Northern Ireland remains aligned with the rest of the UK and remains in same customs territory
• Legislation to ensure workers rights are "every bit as good, if not better" after Brexit - and guarantees of no dilution in environmental standards
• A legal duty to seek changes to the political declaration on future relations with the EU

Carolyn Quinn
PM on BBC Radio 4

Parliament is a place at war. So many backbenchers have said the cabinet is spineless for not telling the PM to go.

BBC News Channel

Former education secretary Nicky Morgan says "we haven't got very long" because of the 31 October deadline for Brexit.

"It will be for Conservative MPs" to choose the final two candidates for a new leader - and the will then be put to a vote of the Conservative Party membership.

Whoever it is, she adds, "they're going to have to accept the Parliamentary arithmetic" on no-deal.

Image source, Reuters

The 1922 Committee - made up of Conservative backbench MPs - was due to meet at 17:00 BST, after a meeting of the executive. That may have now been pushed back a bit.

The current rules dictate that the group can hold a vote of confidence in their party leader if the chairman of the committee, Sir Graham Brady, receives letters calling for it from 15% of the parliamentary party - currently 47 MPs.

However, as the PM survived such a vote in December, the rules say she cannot face another one for 12 months.

One of the 1922's executive secretaries, Nigel Evans, wants this overturned and has said he will propose a change to the group's rules to allow for a no confidence vote to take place against Mrs May immediately.

That makes two of the most senior ministers visiting Theresa May this afternoon.

BBC News Channel

Former minister Tim Loughton says there must be a new leader now. He says he has never before put in a letter to the head of the 1922 Committee calling for a resignation, but has done so now because Brexit "has been played wrong on so many levels".

"Coming back for the fourth time with a deal which is even worse than the first... makes it impossible for me to vote for," the Conservative tells BBC

"We're going backwards," Mr Loughton adds.