THE taoiseach has said he thinks a Brexit deal can be done by November with the border still the most vexed issue facing UK and EU negotiators.
Leo Varadkar warned the damage caused by talks failure to Ireland and Britain would be "immense".
A special meeting of European leaders in Brussels has been mooted for November if the two sides are close to reaching agreement.
Mr Varadkar said: "I do think we'll get there.
"I think we'll get there in November because nobody wants us to end up with a no-deal scenario because the damage for the UK would be immense.
"The damage for Ireland would also be immense and it would have a serious impact on other countries like Belgium, Holland, and France and Denmark.
"So I believe we will get there in November but we are in unchartered territory."
The EU has interpreted a backstop, agreed in principle between the UK and Europe in December, to mean that, in the absence of a trade deal, the north would continue to follow EU rules relating to commerce and thus prevent the imposition of a hard Irish land border.
Britain's prime minister Theresa May has said any move that would see Northern Ireland's regulations differ from the rest of the UK's, likened to putting a border in the Irish Sea, would be a bad outcome.
Her parliamentary allies, the DUP, are strongly opposed to such a scenario.
Mrs May's Chequers plan has been assailed by critics and Brexiteers have reiterated their support for finding a technological solution to the border.
Mr Varadkar said he had sought a lot of counsel in recent months from "wise old heads" who know Europe and know British politics and know Northern Ireland.
"I came away from those meetings with the advice that it's unchartered territory and unpredictable and do your best and I think that was probably the best advice I could have got."
He said Mrs May had reinstated her commitment to having a legally operative backstop as part of the withdrawal agreement while at an informal summit of European leaders in Salzburg recently.
"And the EU 27 again in Salzburg gave their full solidarity behind Ireland and restated our position that there won't be a withdrawal agreement at all, no transition period for the UK if there isn't an Irish protocol, a legally operative backstop as part of that," he said.
Meanwhile, during debate in the Dáil, the taoiseach touched on efforts to restore stalled power-sharing at Stormont.
"I think clarity around Brexit could help.
"Perhaps if by the October summit, or the November summit if there is one, we're in a position to have a roadmap as to how Brexit going to work, what the new relationships are going to look like, we might be in a better position then to bring the parties together again.
"Certainly the government stands ready to do that," he said.
