If European Union leaders insist on Wednesday night on a Brexit extension of nine months or a year, it will because they have no confidence that British prime minister Theresa May can pass the withdrawal agreement within the next few weeks.
"Our experience so far, as well as the deep divisions within the House of Commons, give us little reason to believe that the ratification process can be completed by the end of June. In reality, granting such an extension would increase the risk of a rolling series of short extensions and emergency summits, creating new cliff-edge dates," European Council president Donald Tusk wrote to the EU leaders ahead of Wednesday's summit.
Tusk’s pessimism is shared at Westminster, where a vote on Tuesday authorising the prime minister to seek an extension demonstrated the feebleness of her authority over Conservative MPs. Just 113 voted with the government in favour of the motion, a little over a third of the total, with 97 voting against and a further 80 (including four cabinet ministers) abstaining.
The motion passed comfortably by 420 to 110 on the back of opposition votes and May's remaining hope of passing the withdrawal agreement rests on finding a common approach with Labour. Talks between ministers and their Labour shadows, which broke up after four hours on Tuesday without agreement, are due to resume on Thursday.
Those close to the negotiations agree that both sides are taking them seriously but few at Westminster believe they will unite around a common proposal on Brexit to put before MPs. To do so would require both the prime minister and Jeremy Corbyn to split their parties - the Conservatives over a customs union and Labour over a second referendum.
May’s overture to Corbyn envisaged a second stage to the process if the two parties cannot agree on a common proposal for Brexit. This would see them identify a number of options to be put to MPs in a fresh round of indicative votes. Previous rounds of indicative voting failed to find a majority for any proposal because too few MPs were willing to vote for anything less than their favourite option.
The British government is now considering an alternative approach, which would see MPs voting on various options in the form of amendments to the Withdrawal Agreement and Implementation Bill (WAIB). The bill is a necessary piece of legislation to implement Brexit after the withdrawal agreement is approved.
The government is also required to give MPs a “meaningful vote” on the Brexit deal but it could seek to amend the WAIB to allow the bill’s passage to constitute a meaningful vote. And optimists within the government believe that voting on amendments could see a customs union approved and a second referendum rejected, allowing both the Conservatives and Labour to whip in favour of the bill.
A customs union was rejected by just three votes in the last round of indicative voting but government ministers abstained on that occasion. Free to vote as they choose, more ministers are likely to reject a customs union than to back it, suggesting that it could go down to a bigger defeat next time.
Party discipline is so weak in both the main parties there is no guarantee that the bill would pass even if May and Corbyn whipped in favour of it. Which leads a growing number at Westminster towards the conclusion that this is a House of Commons that cannot deliver Brexit and that the only way to break the deadlock is to call a general election to form a new one.