The Taoiseach has said that it could be Monday before a decision is reached on an extension to the 31 October Brexit deadline.
Earlier, Leo Varadkar said he backed European Council President Donald Tusk's proposal to grant the UK an extension.
Mr Tusk recommended that European Union leaders postpone the UK's departure from the bloc while British Prime Minister Boris Johnson seeks approval of their divorce deal.
The House of Commons last night rejected Mr Johnson's bid to set a tight three-day schedule to approve a Brexit bill this week.
This effectively destroyed London and Brussels' hopes that a treaty for an orderly withdrawal will be ratified before 31 October, which was Mr Johnson's preferred departure date.
Downing Street said that Mr Johnson told Mr Tusk in a phone call today that he "continues to believe that there should be no extension" and that it is in the interests of the EU and UK that Brexit happens on 31 October.
A Government statement said that Mr Varadkar and Mr Tusk also spoke by phone this morning.
It said: "The Taoiseach confirmed his support for President Tusk's proposal to grant the request for an extension which was sought by the UK.
"They noted that it would still be possible for the UK to leave before January 31st 2020 if the Withdrawal Agreement has been ratified in advance of that date.
"The matter is likely to be discussed further at tonight's meeting of the Committee of Permanent Representatives in Brussels."
Breaking: Taoiseach Leo Varadkar will say shortly that Ireland supports a Brexit extension to January 31 2020, following a phone call with @eucopresident President Tusk— Tony Connelly (@tconnellyRTE) October 23, 2019
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Mr Varadkar said the EU Council may have to meet on Monday, or possibly even Friday to decide whether to grant an extension to the UK.
He said he believes the possibility of a no-deal Brexit on 31 October is "reasonably remote" but the Government will continue to prepare for it.
He said if the withdrawal agreement between the UK and the EU is ratified there will be no significant impact on the Irish economy until at least the end of next year.
Mr Varadkar said the transition period, which is basically a stand still arrangement, runs until the end of 2020 and may be extended to allow for ratification as it will have to be approved by the parliaments of 27 EU member states and also some regional assemblies.
Today, Tánaiste and Minister for Foreign Affairs, Simon Coveney has predicted that Irish companies may move north of the border such is the "extraordinary" competitive advantage the Brexit deal offers the region.
Addressing a gathering of business leaders in Belfast, Mr Coveney said the terms of the agreement between the UK and EU presented an "exciting and genuine opportunity" for Northern Ireland to prosper.
Last night, France said it was open to a "technical" Brexit extension of "several days", but it ruled out reopening discussions to renegotiate the deal.
Mr Tusk said the member state leaders could agree in writing rather than holding a summit.
He said that after Mr Johnson's "decision to pause the process of ratification of the Withdrawal Agreement, and in order to avoid a no-deal Brexit, I will recommend the EU27 accept the UK request for an extension".
On Saturday, British MPs forced a reluctant Mr Johnson to request a three-month delay until 31 January next year.
A European official confirmed that Mr Tusk was recommending accepting this date.
But other European sources said member states might argue for a short extension after consulting Mr Johnson's government to decide on the best way to help him get his withdrawal bill through.
In my phone call with PM @BorisJohnson I gave reasons why I'm recommending the EU27 accept the UK request for an extension.— Donald Tusk (@eucopresident) October 23, 2019
Meanwhile, the DUP's Brexit spokesperson said there will have to be a Brexit extension until 31 January.
Sammy Wilson said that his party hopes to use that time to scrutinise the bill and "reverse some of the really bad decisions that have been made".
Speaking on RTÉ's Today with Sean O'Rourke, he said that, at the insistence of the Irish Government, the delicate voting mechanism in the Good Friday Agreement had been "torn to shreds" and the Northern Assembly would struggle to function properly without it.
He said the real worry for Mr Johnson's government was that some amendments will be passed that will change the shape and content of the bill to the extent that the government cannot support it.
Additional reporting: AFP