Whether or not Britain leaves the European Union without a deal is "largely now in the hands" of Brussels, a senior Conservative has told Sky News.
Tory party chairman James Cleverly told Sky News that the EU has to demonstrate a degree of flexibility to avoid Britain leaving without an agreement in place at the end of October.
The decision as to whether we leave with or without a deal is largely now in the hands of the European Union negotiators, he claimed.
The comments come after the PM wrote to the EU’s Donald Tusk, reiterating his opposition to the Irish backstop element of the deal currently on the table.
Mr Johnson said he was willing to give the bloc the commitments it needs that alternatives to the arrangement can be put into effect.
The backstop is designed to avoid the return of a hard border of the island of Ireland if the issue cannot be sorted out between the two sides.
If it kicked in, the UK as a whole would remain in a customs union with the EU, while Northern Ireland would follow further EU rules and regulations in order to keep the border with Ireland – an EU member – frictionless.
But it is opposed by many Conservative MPs and Northern Ireland’s Democratic Unionist Party, which supports the Tories in key Commons votes.
They oppose it because they fear it will weaken the constitutional integrity of the Union – as Northern Ireland would be treated differently to the rest of the UK by following different rules and regulations.
Opponents have also expressed fears Britain could end up being trapped in the arrangement – and by extension the EU.
Alternative arrangements to the backstop have long been touted by supporters of Brexit as a potential solution to the border issue.
They include livestock checks away from the border and a trusted trader programme for goods.
Mr Cleverly told Sky News the letter was the government reaching out to Brussels in order to get a deal.
Although the government is trying to renegotiate the agreement Theresa May struck with Brussels last year, the PM has said he is willing to leave without a deal in place if necessary.
During his campaign to be PM, Mr Johnson described the chances of such a scenario as a million to one, but Mr Cleverly declined to be drawn on what the odds are now.
I’m not going to speculate on the odds, he said.
But the simple fact is that the EU needs to demonstrate a degree of flexibility.
And Mr Cleverly said it would in large part be down to Brussels as to whether no deal happens.
Ultimately, the European Union has got to recognise the reality, which is that we are going to leave, he said.
The decision as to whether we leave with or without a deal is largely now in the hands of the European Union negotiators.
If they recognise the reality, that the backstop has prevented us from getting a deal through the House [of Commons], then they can remove that.
We can work on the alternative arrangements, which is explicitly the way of getting round the Irish border, and we can leave with a deal.
But we will be leaving on 31 October, come what may – and I think the recognition of that will help the EU negotiators understand what they need to do to make sure that a deal can get through the House.
The PM will this week head to Berlin and Paris as he tries to secure a new Brexit deal.
Mr Johnson will hold talks with German Chancellor Angela Merkel on Wednesday, followed by discussions with French President Emmanuel Macron on Thursday.
Details of the letter emerged as a senior US politician warned that legislators would move to block a future trade deal if it puts the Good Friday Agreement at risk by introducing a hard border on the island of Ireland.
US Senate majority leader Chuck Schumer has written to US Secretary of State Mike Pompeo to warn that Congress could work on a cross-party basis to block a deal.
Mr Johnson and Donald Trump spoke by phone on Monday, with the US president saying the two countries could work rapidly on a post-Brexit free trade deal.