Theresa May will insist the Brexit deal is 95% complete as she faces MPs after a weekend of vicious attacks from within her own ranks.
In a Commons statement after talks with EU leaders in Brussels, the British Prime Minister will say the "shape of the deal across the vast majority" of the withdrawal agreement is now clear.
She will tell MPs that since last month's fractious summit in Salzburg, "important progress" has been made on issues like security, transport and services.
Protocols have been developed on how Brexit will impact Gibraltar and the UK's military base in Cyprus.
"And all of this from the last three weeks alone, is in addition to the agreements we had already reached," she will say.
Mrs May will tell the Commons that "taking all of this together, 95% of the withdrawal agreement and its protocols are now settled".
But she will add: "As I set out last week, the original backstop proposal from the EU was one we could not accept, as it would mean creating a customs border down the Irish Sea and breaking up the integrity of the UK.
Furious backbenchers warned the Prime Minister she is "drinking in the last chance saloon" after tensions flared over her negotiating strategy following a Brussels summit.
Senior Brexiteer Theresa Villiers criticised "disturbing" anonymous briefings to Sunday newspapers, including claims the PM was entering the "killing zone".
But Brexit minister Suella Braverman said her colleagues were "free to express themselves in the way they wish" and repeatedly refused to say she would back Mrs May in a confidence vote.
British Brexit Secretary Dominic Raab said the exit agreement must be finalised by the end of next month to allow new laws to be put in place in time for exit day.
Mr Raab suggested a transition extension could run for three months, but said the move would have to "solve" the Irish backstop issue.
Labour has warned Mrs May that it will not back her Brexit blueprint when it reaches the Commons.
Shadow Brexit secretary Keir Starmer said there is a "real lack of confidence" that Mrs May can bring back "anything by way of a good deal".