Brexit: Irish PM speaks to President of EU Commission
The taoiseach (Irish prime minister) and President of the European Commission spoke by phone on Wednesday evening.
Leo Varadkar and Jean Claude Juncker both agreed the withdrawal agreement is "the best outcome available".
They agreed that the proposed deal "cannot be reopened or contradicted".
It comes as Mr Varadkar's party agreed to extend their confidence and supply agreement with their current government partners, Fianna Fáil.
Earlier on Wednesday, Fianna Fáil's leader Micheál Martin ruled out an election and said the Irish government can continue throughout 2019 due to the uncertainty over Brexit.
His party is the largest opposition party in the Republic of Ireland.
"Fianna Fáil is determined that the political chaos we see in London will not be allowed to spread to Ireland," he said.
Mr Martin made the comments ahead of a Conservative party parliamentary vote of confidence in Prime Minister Theresa May.
It supports the minority Fine Gael-led government.
That government, led by Taoiseach (Irish prime minister) Leo Varadkar, was formed in 2016 following an inconclusive general election and weeks of negotiation.
Fianna Fáil agreed to support it for three budgets and in confidence motions.
Mr Varadkar said in August that he wanted the arrangement to continue due to uncertainty over the Brexit process.
Mr Martin told the Dáil (Irish parliament) on Wednesday that there must be an ability to put the national interest above party interest.
"The only thing which is clear is that no one has the faintest idea what the course of Brexit will be in the coming weeks and months, and potentially for much longer than that," he said.
"With the exception of the fundamentalist fringe of the Conservative Party and, unfortunately, the DUP, all accept the idea of a guaranteed open border in Ireland - but they do not agree on the wider issue of the UK's relationship with the European Union," he said referring to the Backstop, the insurance policy to avoid a return to a hard border after Brexit.
The DUP and Brexiteer MPs have vowed to reject the deal unless the backstop is ditched, because they say any differences for Northern Ireland could threaten the union and damage the economy.
That is because if the backstop took effect, Northern Ireland alone would align with the EU single market in some areas, meaning new regulatory barriers between GB and NI - Labour has described this as a "de facto Irish Sea border".
Mr Martin said that under normal circumstance an election would appropriate.
"However these are not normal times and Ireland is immediately confronted with one of the biggest threats for many decades," he said.
"We simply do not believe that the national interest could in any way be served by taking up to four months during next year to schedule and hold an election campaign and then form a government," he added.
Tanáiste (deputy prime minister) Simon Coveney thanked Mr Martin saying that the decision showed maturity.
He said he expected the extension of the agreement to go "well into 2020" and that it was not a free pass for the government but an extension of the existing agreement.
Mr Martin's decision to continue with the confidence and supply agreement was criticised by Sinn Féin leader Mary Lou McDonald.
Accusing Fianna Fáil of running away from the Irish electorate she said the continuing agreement was delivering failure and homelessness.
Mr Martin also said that Northern Ireland has suffered from "political game-playing and the absence of a democratic voice".
He claimed the majority in Northern Ireland want to remain in the European Union and also supported the Brexit deal negotiated by UK Prime Minister Theresa May.