The Taoiseach says the government does not have a perfect solution for avoiding a hard border if there is a no deal Brexit.
Leo Varadkar says he has been looking at a number of possible solutions with the European Commission.
They include treating the entire island of Ireland as one economic zone to protect the EU's single market.
Other options are checks on goods at business level or at factories.
But Mr Varadkar says none of those are ideal scenarios.
"We don't have a perfect solution. We all know that the best solution for Ireland would be for the UK to remain in the EU, but they have decided that is not possible," said Mr Varadkar.
"The second best solution would be for them to stay in the single market and the customs union which effectively is a transition period.
"But they say they are not willing to do that...maybe for a few years, but not indefinitely.
"And the other best solution is a backstop, either a UK wide backstop or a Northern Ireland backstop. We don't mind which one it is."