John Bercow has warned Tory leadership contenders threatening to crash out of the EU without an agreement in October that the Commons is likely to block it.

The Speaker dismissed expert opinion that MPs had lost their opportunity to stop a no-deal Brexit, insisting: “The idea the House won't have its say is for the birds.”

Boris Johnson has insisted the UK will leave on 31 October “deal or no deal” – with rival contenders quick to adopt the favourite’s hardline stance.

But, speaking in America, Mr Bercow said: “The idea that parliament is going to be evacuated from the centre stage of debate on Brexit is unimaginable.”

He agreed leaving without a deal was the default position, but added: “There is a difference between a legal default position and what the interplay of different political forces in parliament will facilitate.”

The comments come after Dominic Raab, a leading Brexiteer candidate, predicted that MPs would fail to prevent him carrying out a Halloween night crash-out, if he wins the race to No 10.

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They will increase the expectation the Mr Bercow will find a way for MPs to stage a vote – perhaps on an emergency debate, as he has hinted in the past – allowing a fresh law to block no-deal to be passed.

Some pro-EU Tories – including Philip Hammond, the chancellor – have floated toppling their own government by supporting a no-confidence vote, as another mechanism.

Mr Bercow also said he had “nothing to add to or subtract from” his past attack on Donald Trump, when he banned him from speaking to parliament.

The ban is widely seen as having prevented the US president from making an address on his State Visit next week – with both No 10 and Washington keen to avoid further controversy.

Addressing an event in Washington, the Speaker admitted he made an error when he invited the Chinese president, Xi Jinping – a leader condemned for human rights abuses – to address parliament.

“You make mistakes. Looking back, do I think there’s a powerful argument that says perhaps the Chinese president should not have been invited? Was it necessarily the right decision? No,” he said.

And he risked stepping into the leadership contest by praising both Michael Gove and Jeremy Hunt as “extremely capable ministers” with “the intellectual self-confidence as well as the communication skill" to thrive in the chamber – as well as hailing their “pursuit of consensus”.

The Commons was able to pass a law to block no-deal when Theresa May threatened a no-deal, by passing a motion when her Brexit deal was put before MPs.