Taoiseach Leo Varadkar has called on Sinn Féin to take up their seats at Westminster or else consider resigning them ahead of a crucial week for British prime minister Theresa May.
Mr Varadkar says he expects the British parliament will "sooner or later" support the Brexit deal which has been negotiated between the EU and the UK and agreed upon this weekend in Brussels.
He said if Sinn Féin felt they cannot take up their seats because of their absentionist policy, they should consider resigning ahead of a vote on the deal in the House of Commons.
"Sinn Féin is an unusual party in that it is not taking up its seats in Westminster for one reason and it isn't taking up its seats in Stormont for another.
“Generally people who get involved in politics get involved because they want to make a difference and use the democratic process to get good outcomes for citizens.
“If they are not willing to take up their seats because they feel they can’t, because they got elected on the basis of abstentionism, they do have the option now of resigning their seats and allowing the people in those constituencies decide whether or not they want to have a say when this vote comes to Westminster.”
He also sounded a note of optimism around whether the deal can be ratified by the UK parliament.
“I think it is likely that the UK parliament sooner or later will agree to what has been agreed by the 28 member state governments.”
Mr Varadkar said there had been a lot of focus on the backstop - the insurance mechanism to avoid a hard border in Ireland - but said the arrangement offered benefits to the UK also.
“This is the best deal that was available to the UK. I know there is a lot of focus on the backstop but bear in mind one of the big benefits for the UK of the backstop is it provides for a single customs territory if we cannot agree a future relationship as President Macron pointed out yesterday.
That means that even if we can’t negotiate a future relationship, the UK will continue to have access to EU markets through a single customs territory.”
He said that EU leaders had collectively agreed over the weekend not to speculate too much on what would happen in a no-deal scenario.
"What we decided to do at the European Council meeting was to collectively not speculate too much on a no deal scenario or on alternatives to what has been agreed.
We don’t want to give the wrong impression to people whether they are passionate Remainers or passionate Brexiteers that there is another deal could command the support of 28 members states, there is not. It is this deal or a no deal scenario.”
Mr Varadkar said the government would continue to publish details around its contingency plans where possible.
