Theresa May will insist that she will deliver a Brexit deal that “honours our commitments to Northern Ireland”, admitting that she knew it was a “concerning time”.
The prime minister will use her speech to ensure people that she can secure a Commons majority for a Brexit deal that "commands broad support" in Northern Ireland as efforts continue to find an alternative to the controversial backstop.
On Wednesday Mrs May will hold talks with Northern Ireland's political leaders including the DUP's Arlene Foster, who has promised to tell the prime minister the proposed border backstop "drives a coach and horses through the Belfast Agreement's principle of consent" and would effectively create a new border between Northern Ireland and the rest of the UK.
But Brussels has restated its opposition to any attempt to reopen the withdrawal agreement, insisting the backstop was the "only operational solution" to the border question.
In her speech, Mrs May will say: "I know this is a concerning time for many people here in Northern Ireland.
"But we will find a way to deliver Brexit that honours our commitments to Northern Ireland."
'Shape the opportunities of the future'
The backstop is effectively an insurance arrangement required by the EU to ensure the border between Northern Ireland and the Republic remains open if no wider deal is agreed on future UK/EU trade.
It would see the UK enter into a temporary customs union with the EU if no trade deal is sealed by the end of a transition period after Brexit, which lasts until December 2020 and could be extended to the end of 2022.
Northern Ireland would also abide by EU single market rules on goods, to avoid any need for regulatory checks of products crossing the border.
And the DUP strongly rejects any measure which could lead to divergence between Northern Ireland and the rest of the UK, effectively creating a regulatory border in the Irish Sea.
MPs voted last week to say they would only back Mrs May's Withdrawal Agreement if the backstop was replaced by "alternative arrangements".
In her speech, Mrs May will say she will find a solution "that commands broad support across the community in Northern Ireland" and "secures a majority in the Westminster Parliament, which is the best way to deliver for the people of Northern Ireland".
And she will call for "steps to move towards the restoration of devolution" so that Northern Ireland's politicians "can get back to work on the issues that matter to the people they represent".
Mrs May will say: "The measure of this moment in Northern Ireland's history must be more than whether we avoid a return to the challenges of the past.
"It must be how, together, we move forwards to shape the opportunities of the future."