Boris Johnson's bid to avoid delaying Brexit has failed.

The House of Commons Speaker ruled that he could not hold a vote on whether to approve his Brexit deal, after a similar bid was blocked on Saturday.

Johnson must now bring forward the legislation designed to put Brexit into EU law.

He will now face renewed attempts by MPs opposed to Brexit, to unpick the fragile coalition of support he has for his deal.

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Boris Johnson's bid to hold a vote on his Brexit deal and avoid delaying Britain's exit from the EU has been blocked by the House of Commons speaker John Bercow.

Bercow told the House of Commons that Johnson could not hold a second vote on his Brexit deal, after a similar bid was blocked on Saturday, because convention does not allow the government to hold two votes on the same question in the same session of parliament.

"Today's motion is in substance the same as Saturday's motion and the House has decided the matter," he told MPs.

It makes the chances of Johnson delivering Brexit by the Halloween deadline significantly tighter, as he will now need to first pass the legislation required to enact his Brexit deal through Parliament before gaining approval of the House.

Watch Bercow block vote on Johnson's Brexit deal

—BBC Breaking News (@BBCBreaking) October 21, 2019

Failure to gain their approval will mean that the EU is likely to agree to Johnson's request, made on Saturday, to delay Brexit until next year.

"Today's circumstances are in substance the same as Saturday's circumstances," Bercow said."The motion will not be debated today as it would be repetitive and disruptive to do so."

A spokesperson for the prime minister accused Bercow of seeking to block Brexit.

"We are disappointed that the Speaker had yet again declined to give us a chance to deliver on the will of the people," they said at a press briefing attended by Business Insider.

Can Boris Johnson still get Brexit done by October 31?

Boris Johnson UK Parliament The UK government will now push ahead in an attempt pass Brexit legislation through the House of Commons by the end of this week.

It would then need to go to the House of Lords, who would be likely to amend the bill further. Even with a fair wind, tying the whole process up before October 31 looks incredibly difficult.

However, it's not impossible and on Tuesday, the government will bring forward two votes which will get the process moving.

The first critical vote will be the second reading of the Withdrawal Agreement Bill. MPs will be asked to let the Brexit legislation progress pass through to the next stage of its journey into becoming law. As things stand he appears to have a good chance of succeeding here, albeit by only a slim majority.

The danger for Johnson will be in what happens afterwards.

MPs will have the chance to first debate the "programme motion" for the following stages of the bill. This will set out the timetable for the legislation and there is a chance that parliament will decide that they want more time to consider the bill than the October 31 deadline allows them. If they do, then Johnson could decide that parliament is determined to block Brexit and instead accept an extension from the EU and them attempt again to call a general election.

However, assuming that the government's timeline is approved, then MPs will then move on to debating the substance of the bill itself.

This is where things could get tricky for them. Among the possible amendments to the Brexit bill are a call for the government to commit to retaining current customs relationships with the EU, or to hold a second referendum on Brexit.

If the vote on a customs union is passed, the bill could in theory still continue through parliament. However, Johnson would risk losing the support of his own MPs for the deal were this to happen.

The second possibility is that MPs agree to only support the deal if Johnson agrees to holding a public second referendum on whether to approve it. Were this to happen then Johnson's deal would need to be fundamentally renegotiated and he would likely abandon it altogether and attempt to force a general election.