The Prime Minister will meet the main Northern Irish parties later as she steps up her bid for a breakthrough on the backstop.
Theresa May has already had conversations with business and community leaders during her two-day trip to Belfast.
She is expected to meet the Democratic Unionists and Sinn Fein among others on Wednesday.
The premier has suggested that she is seeking “changes” to the controversial backstop in her Brexit deal, rather than its total removal from the UK’s EU Withdrawal Agreement.
In a speech in Belfast, the Prime Minister restated her “unshakeable” commitment to avoiding a hard border in Ireland after Brexit, pledging: “The UK Government will not let that happen. I will not let that happen.”
But asked how she could convince the people of Northern Ireland to accept a Brexit deal which was stripped of the backstop, Mrs May said: “I’m not proposing to persuade people to accept a deal that doesn’t contain that insurance policy for the future.
“What Parliament has said is that they believe there should be changes made to the backstop.”
It was in that light that she was working with MPs, the Irish government and the EU to find a way to meet the commitment to take Britain out of the EU on March 29 with a deal which avoided a hard Irish border, she said.
The Irish Government accused the Prime Minister of harbouring unrealistic expectations over the backstop.
The mechanism has polarised nationalists and unionists.
Many unionists believe the “insurance policy” to preserve a frictionless frontier on the island of Ireland could threaten the integrity of the UK if Northern Ireland’s customs regulations varied from Great Britain after Brexit.
Nationalists and many business leaders fear major disruption to trade and a hard border threatening peace process gains if no deal is struck and the backstop is not triggered.
Meanwhile, Irish Taoiseach Leo Varadkar will travel to Brussels for meetings with European Council president Donald Tusk and European Commission president Jean-Claude Juncker.
Mrs May is due to visit the Belgian capital on Thursday, where she will hold a series of talks with key figures including Mr Tusk, Mr Juncker, European Parliament president Antonio Tajani and the European Parliament’s chief Brexit negotiator Guy Verhofstadt.
It will be the Prime Minister’s first chance to hold first face-to-face talks in Brussels since the Withdrawal Agreement reached last November was rejected by the House of Commons.
And it comes a week after MPs voted for an amendment tabled by Conservative grandee Sir Graham Brady and backed by the Prime Minister which “requires the Northern Ireland backstop to be replaced with alternative arrangements to avoid a hard border”.
Mrs May will seek to secure changes which can persuade MPs to support her deal in a series of votes expected on February 14.
In Westminster, the working group bringing together senior Eurosceptic and former Remain-supporting Tories will continue efforts to agree alternatives to the backstop along the lines of the Malthouse Compromise.
Talks involving Conservatives including Brexiteers Iain Duncan Smith, Theresa Villiers, Steve Baker and Owen Paterson along with former Remainers Nicky Morgan and Damian Green will continue in Whitehall, chaired by Brexit Secretary Stephen Barclay.
The first meeting on Monday was described as “detailed and constructive” by the Brexit department.