House of Commons Speaker John Bercow has scuppered any chance of another Commons vote on Theresa May’s Brexit withdrawal agreement before Thursday’s EU summit.

Mr Bercow ruled that the Prime Minister cannot bring her EU withdrawal deal back before MPs unless it is substantially different from the package which was decisively defeated last week.

Mr Bercow’s ruling, announced in an unexpected statement to the Commons, throws a further obstacle in the way of the Prime Minister’s scramble to get a deal agreed by the scheduled date of Brexit on March 29.

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Downing Street has indicated that Mrs May will not table a motion on a third “meaningful vote” ahead of Thursday’s EU summit in Brussels unless there is a realistic prospect of securing a majority in the Commons.

If no vote takes place over the coming days, she is expected to ask the leaders of the remaining 27 EU members for a lengthy extension to the two-year Article 50 negotiation process, delaying Brexit day for months or even years beyond March 29.

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It is widely expected that the PM will then make a last-ditch attempt to get her deal through the Commons next week, effectively presenting MPs with a choice between the Withdrawal Agreement which they have already rejected twice, or a long wait for Brexit.

But Mr Bercow’s ruling could make that plan impossible, unless Mrs May is able to negotiate some change to her deal before presenting it once more to MPs.

There was no immediate response from Downing Street to the statement by Mr Bercow.

The Prime Minister’s official spokesman said: “The Speaker did not warn us of the contents of the statement or indeed the fact that he was making one.”

The Speaker cited the Commons rulebook Erskine May as he set out a convention dating back to 1604 that a defeated motion cannot be brought back in the same form during the course of a parliamentary session.

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He said it was within the rules for a second vote to be held on the Withdrawal Agreement in March, because it had been substantially revised – including by the addition of three new documents – since its defeat by 230 votes in January.

“If the Government wishes to bring forward a new proposition that is neither the same nor substantially the same as that disposed of by the House on March 12, this would be entirely in order,” said Mr Bercow.

“What the Government cannot legitimately do is resubmit to the House the same proposition – or substantially the same proposition – as that of last week, which was rejected by 149 votes.

“This ruling should not be regarded as my last word on the subject. It is simply meant to indicate the test which the Government must meet in order for me to rule that a third meaningful vote can legitimately be held in this parliamentary session.”