EU and UK negotiators have agreed a text that deals with the Irish border, RTÉ News understands.
The text was agreed at around 9pm last night and then transmitted to Downing Street.
While two well-placed sources have confirmed that the text was "as stable as it can be", they say it would not be correct to say that the negotiations have "concluded".
According to both sources, there will be one backstop to avoid a hard border on the island of Ireland.
The backstop will come in the form of a temporary UK-wide customs arrangement, with specific provisions for Northern Ireland, which go deeper on the issue of customs and alignment on the rules of the single market than for the rest of the UK.
It is understood the text has an agreed review mechanism.
While the text is regarded as "stable", it is understood there is further shuttling between London and Brussels.
RTÉ News understands that while the main backstop focuses on a UK-wide customs arrangement, there will be specific provisions within the text and within annexes for Northern Ireland, should the UK-wide arrangement not prove sufficient to avoid a hard border.
Cabinet meeting tomorrow to discuss text
A Government spokesperson has said Taoiseach Leo Varadkar has called a Cabinet meeting for 9.30am tomorrow to consider developments.
Cabinet was notified by the Taoiseach this morning to be on standby for another meeting on Brexit this week at short notice.
The Taoiseach, Tánaiste Simon Coveney, Minister for Finance Paschal Donohoe and Minister for European Affairs Helen McEntee discussed the state of play with senior government officials this evening.
The Government wants to allow the British government to have time and space to consider the draft agreements.
It will not be commenting any further until the Taoiseach and Tánaiste have had an opportunity to brief their colleagues and the Dáil.
A Government source said there had been "close contact" between Irish and EU officials.
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Opposition parties at Leinster House have given a cautious response to the reports.
Fianna Fáil's Brexit spokeswoman Lisa Chambers said a deal, if concluded, could be positive.
She told RTÉ News: "If that turns out to be true, we would very much welcome that."
However, she added: "Detail is important. We would need to see the text."
Sinn Féin's Brexit spokesman David Cullinane said: "We have not seen the detail of what's been agreed. We have to wait and see, and study it in full.", while the party leader Mary Lou McDonald said the withdrawal agreement must give legal effect to Taoiseach's 'cast iron' guarantee that there will be no hard border in Ireland.
Labour leader Brendan Howlin was also cautious, saying his party "needs to space and time to assess the legal interpretation of the agreement. This is something you have to look at the detail".
Independent TD Thomas Pringle said: "We have to see the detail. We have to hold comment until then."
He added any Brexit agreement "potentially will have a very negative effect for the border if it's wrong. We need to be sure it is right".
Additional reporting Mícheál Lehane and Paul Cunningham