Irish Taoiseach Leo Varadkar has suggested the island of Ireland could enjoy post-Brexit common regulation in the same way as the Republic and the UK have a common travel area.
Mr Varadkar said the legal text on Britain's withdrawal from the EU states there will not be a hard border with Northern Ireland.
"Some people were trying to suggest in the last couple of weeks that we over-spun, or oversold what was achieved in December. I think people will see today that that charge from the opposition (parties in Ireland) and others is not correct," he said.
Mr Varadkar told Newstalk radio: "Option C is how we can avoid a hard border. We set that out in legal terms today, it is very clear.
"In the same way that we have a common travel area between Britain and Ireland we could have a common regulatory area involving Northern Ireland.
"A lot of the rules of the customs and single market would apply in the north and that means there doesn't have to be a hard border so it is do-able. We've set it out in a legal text."
Mr Varadkar said his Government would prefer to see what is being classed as "Option A" - a new relationship between the UK and EU that is so close that a border is unnecessary.
"It's up to the UK to bring proposals to the table to make that possible and I hope that we will see some indication in Theresa May's, the Prime Minister's speech on Friday as to how they intend to do that," Mr Varadkar said.
"It's not OK for people - whether it's pro-Brexit politicians in Britain or people from parties in Northern Ireland - to just say no now. It's incumbent on them if they can't accept the backstop then they must detail how Option A or B would work.
"It's really up to those who can't accept the backstop to actually come up with those alternative solutions. And actually write them down. It can't be theoretical stuff about congestion charges."