The Taoiseach Leo Varadkar has said he 'doesn't see much room' for re-negotiation of the draft Brexit deal.
It had been suggested that a new Brexit secretary in the UK could look to change some elements of the agreement.
British Prime Minister Theresa May also saw several high-profile resignations on Thursday over opposition to the deal.
Mrs May has refused to say if the DUP, who is propping up her Westminster government, will vote for the deal.
She also firmly defended the draft deal on Thursday, as she faces increasing pressure from within her own Conservative party.
But Mr Varadkar has said there simply is not time to make changes.
"To be honest I don't see much room for re-negotiation.
"This is a withdrawal agreement which took the best part of two years to negotiate involving 28 countries - all of whom have their particular concerns and interests.
"I think if you start trying to amend it or unpick it, then you might find that the whole thing unravels."
"I certainly don't think it could be re-negotiated in the period that's left - we're only a few months away from Brexit now.
"I think any re-negotiation would involve postponing Brexit, and the people who oppose it don't seem to want that".
Taoiseach Leo Varadkar says he 'doesn't see much room' for renegotiation of the draft #Brexit deal - suggesting it may unravel if it is picked at. "I certainly don't think it could be renegotiated in the period that's left" pic.twitter.com/RYLoghUka9
— Jack Quann (@jqbilbao) November 16, 2018
Preparations for no-deal
He expects the European Council to agree the deal next week - but admitted Mrs May has "quite a battle to get it through the House of Commons".
But he added that a no-deal scenario could see a hard border in Ireland.
"We're continuing to make preparations for a no-deal Brexit... The truth is no country would be fully prepared for a no-deal Brexit."
"I think in a no-deal scenario, it would be very difficult to avoid a hard border - because of the obvious fact that as Ireland remaining part of the European Union, we would no doubt be asked to implement European law; and then also the United Kingdom, having left the European Union, would seek to join the World Trade Organisation, and they would have to implement World Trade Organisation rules.
"So those hard Brexiteers who say that, somehow, just through good political will you can avoid a hard border - that doesn't make sense".
