The UK government has submitted documents to the European Commission that outline in writing for the first time Boris Johnson’s ideas on how to end the Brexit impasse, three sources have told BuzzFeed News.

The text sets out some of the UK’s initial thoughts on how to get around the issue of the so-called backstop. The sources would not be drawn into the precise details of the content of the documents submitted by the UK, with one of them stressing, however, the need to keep expectations in check.

The backstop is an insurance policy guaranteeing that the border between Northern Ireland and the Republic of Ireland remains open after Brexit in all circumstances and scenarios, while also protecting the integrity of the EU’s single market. The UK and the EU both committed to keeping the border open in December 2017, but Johnson has repeatedly pledged to ditch the backstop.

On Wednesday, Antti Rinne, the prime minister of Finland — which currently holds the rotating presidency of the European Council — warned that Johnson had to send concrete proposals by the end of this month if there was to be any chance of an agreement when the leaders of the EU’s remaining 27 member states meet in Brussels Oct. 17–18.

In recent weeks, there has been much speculation that Johnson could move towards a Northern Ireland–only backstop, which would effectively maintain the status quo in Northern Ireland by keeping it in the single market and customs union until an alternative arrangement could be found that would avoid hard border with the Republic of Ireland. Such an option, which would allow the rest of the UK to diverge from the EU’s regulatory regime and standards, was first proposed by the EU some two years ago. Brussels has consistently said that it remains on the table.

Johnson's predecessor as prime minister, Theresa May rejected the solution, however, saying that no British prime minister could ever accept it because it would undermine the constitutional integrity of the UK.

