JOHN Bercow, the Commons Speaker, has once again riled UK ministers after failing to select a so-called “lifeline amendment” in tonight’s Brexit vote that they believed could have limited the scale of Theresa May’s expected defeat.

The proposed change, quietly supported by the UK Government, had been tabled by Tory backbencher Andrew Murrison and supported by 29 of his colleagues, which called for the Irish backstop to be limited to just a year until the end of 2021. A similar amendment by Conservative MP Hugo Swire, which would have given MPs a vote on implementing the backstop, was also not selected.

The hope from Whitehall was that, if passed, either amendment could have minimised the scale of defeat and been used by the Prime Minister to pressure Brussels into further concessions.

But Mr Bercow, who last week enraged the Government by breaking with convention on parliamentary procedure, rejected the two Tory backbench amendments.

At the start of the fifth and final day of the Brexit debate, he decided only four of more than a dozen amendments should be put before the main motion is voted upon. In effect, this means that the chances are there will be around 8.15pm a straight vote on the May Plan, thus raising the prospect of a sizeable and humiliating defeat for the PM.

The amendments to be voted on from 7pm are:

*Labour’s, which rejects Mrs May’s compromise proposal because it fails to provide a permanent customs union and "strong single market deal" as set out in its "six tests";

*the SNP’s, which declines to approve the PM’s proposed deal and calls for the UK's departure from the EU to be delayed until another withdrawal deal is agreed;

*Tory backbencher Sir Edward Leigh’s, which makes clear the backstop is temporary and says if the backstop did not end by the end of 2021, then the entire Withdrawal Treaty would be scrapped and

*Conservative MP John Baron's, which would enable the UK to terminate the backstop at any time and without the agreement of the EU.

Mr Bercow explained that they would be voted on in this order and that Mr Baron’s amendment would be called only if Sir Edward’s was rejected.

During Commons exchanges, Mr Swire launched a thinly-veiled attack on the Speaker, asking Geoffrey Cox, the Attorney General, if he believed the “non-selection” of his and Mr Murrison’s amendments would make the “Government’s challenge harder to convince those of us who are still concerned about the implications of the backstop”.

Mr Cox replied that he had never underestimated the challenge facing the Government but said that after reflection he had concluded the risk of the backstop was an “acceptable” one.

Meanwhile, the Democratic Unionists pointed out that what MPs were being asked to vote on this evening was the “legally-binding Withdrawal Agreement” negotiated with the EU, which did not contain any end date on the backstop.

The party said in a statement: “The Prime Minister has known for many weeks what we require. Amendments tabled in Parliament will have no bearing on the legal status of what has been negotiated. What is required is for the Prime Minister to go and secure legally-binding changes as she promised.

“Today’s very belated amendments are part of the internal parliamentary games and do not change the need to secure legally-binding changes,” it declared.

At the weekly Cabinet meeting, Mrs May reminded colleagues that the Government was the “servant of the people”.

Her spokesman said senior ministers had discussed the process "before, during and after the vote," but declined to give any details on a Plan B.

Asked if the PM felt she had the full confidence of her Cabinet going into the vote, he replied: "Absolutely."

Mrs May will close the debate at around 6.30pm. Voting will then take place and is expected to finish just before 8.30pm.

The spokesman explained that the PM would respond "quickly" to the vote result from the Commons dispatch box. The general view at Westminster is that she will simply make a holding statement before, possibly, returning to Brussels to seek more concessions later this week.

However, that could prove problematic if she suffered a massive defeat as EU leaders would be reluctant to give ground if they believed it was simply impossible for her to get any version of her Brexit Plan through the Commons.

Alternatively, Mrs May could opt to bring back the compromise deal to the House for a second - or possibly even a third - time in an attempt to wear down the opposition. Scottish Secretary David Mundell has already suggested this might be a way forward; tacitly confirming that the expectation is that the PM’s plan will be rejected.

However, Jeremy Corbyn is expected to create more parliamentary drama by tabling a no-confidence motion tonight following the PM's expected defeat with a vote taking place tomorrow after Prime Minister’s Questions.

Earlier today, Labour’s Hilary Benn pulled his amendment to the Government's Withdrawal Agreement motion, which would have rejected both the PM's deal and leaving the EU without a deal.

The backbencher, who is chairman of the Commons Brexit Committee, had Tory support for his proposal but tweeted that he had decided to act because "it's vital that we now get the clearest expression of view from the House on the Government's deal".

The Labour leadership wants the cleanest of votes on the May Plan in order to maximise the scale of her expected defeat.

Up until the vote, the PM is expected to have private meetings with a number of wavering Tory MPs; she spoke to 20 over the weekend.

Michael Gove, the Environment Secretary, referenced the popular television fantasy drama Game Of Thrones when he warned colleagues of the consequences of rejecting the May Plan, telling BBC Radio 4’s Today programme: “If we don't vote for the deal tonight, in the words of Jon Snow: 'Winter is coming.'”

The Scot added: “If we don't vote for the deal tonight, we will do damage to our democracy by saying to people we are not going to implement Brexit and the opportunity that all of us have to live up to our democratic obligations is clear."