After talks between Leo Varadkar and Boris Johnson prompted a new surge of optimism that a Brexit deal could be reached, intensive talks over the weekend were described by the EU’s chief negotiator Michel Barnier as “difficult”, suggesting once again that hopes of an agreement were in the balance.

Over the next six days, most observers expect that clarity over whether a deal can be done – or if an extension might be plausible – will finally arrive. Here are the key moments ahead:

Monday

The Queen’s speech, outlining the government’s plans for legislation, will include details of the withdrawal agreement bill, to be voted on if the EU agrees to a Brexit deal this week. Among the other 22 bills are tougher sentences for violent and sexual offences and scrapping the current rail franchise system. The Scottish National party conference continues in Aberdeen.

Tuesday

MPs debate the Queen’s speech, which can take up to five days before a vote is held. The chief Brexit negotiator, Michel Barnier, will meet EU ministers before the European council summit on Thursday. Agenda papers say he will discuss the “state of play regarding Brexit”.

Thursday

The EU summit begins in Brussels. Johnson and his team will attend, but it may already have become clear by that point whether a deal is doable. A fourth day of debate of the Queen’s speech will he be held in the Commons.

With parliament not scheduled to sit on Friday, Thursday would be the government’s last chance to table a motion scheduling a Saturday session in the House of Commons.

Friday

The EU summit continues with Brexit talks, which is the last item on the agenda – and may turn its attention to the length of a potential extension.

Saturday

The first time the Commons meets on a Saturday since the Falklands war has been labelled “super Saturday”. Johnson will either present an EU-backed Brexit deal or set out his next steps.

Under the terms of the Benn act, Johnson should write a letter to the EU requesting an extension if parliament has not approved a Brexit deal by 11pm.

It is unclear whether the government will table the full withdrawal agreement implementation bill, which rebel MPs could seek to amend to bring about a referendum, or just a motion setting out the terms of the proposed deal.