Theresa May is taking an upbeat stance on securing a Brexit deal, as Ireland insists the UK must stick to its commitments on keeping a soft border with the Republic.
The Prime Minister is using an address to the Commons on Monday to stress that while a new air of optimism on a final settlement has emerged, nothing is agreed until everything is agreed.
The comments come after Dublin expressed concern that Brexit Secretary David Davis insisted the last minute deal agreed on Friday to allow trade talks to start was "a statement of intent" rather than legally enforceable.
The Irish government branded the view "bizarre" and insisted that an agreement the UK will have "full alignment" with the EU on issues that impact on Northern Ireland was "binding".
The spat between Dublin and London emerged as Mrs May was chairing the first Cabinet meeting on Monday since her dramatic pre-dawn dash to Brussels to agree a way forward with European Commission president Jean-Claude Juncker last week.
With some Tory Brexiteers expressing concern that the UK has agreed to pay a £39 billion exit bill, let the European Court of Justice have a legal role for a further eight years, and pledged the "full alignment" on Irish border issues, the Prime Minister is saying she has been consistent in her approach.
The PM is expected to tell the Commons: "This is not about a hard or a soft Brexit.
"The arrangements we have agreed to reach the second phase of the talks are entirely consistent with the principles and objectives that I set out in my speeches in Florence and at Lancaster House.
"I know that some doubted we would reach this stage.
"Of course, nothing is agreed until everything is agreed.
"But there is, I believe, a new sense of optimism now in the talks and I fully hope and expect that we will confirm the arrangements I have set out today in the European Council later this week.
"In doing so we can move on to building the bold new economic and security relationships that can underpin the new deep and special partnership we all want to see.
"A partnership between the European Union and a sovereign United Kingdom that has taken control of its borders, money and laws once again."