Politicians in London are making a "terrible political miscalculation" if they think there's a better Brexit deal on the table, the Taoiseach has said.
Leo Varadkar was speaking in the wake of comments made during the Conservative leadership campaign in the UK.
With nominations now formally closed, the contest is well underway, with the various candidates weighing in on their proposed Brexit approach.
Frontrunner Boris Johnson has threatened to hold back the €43bn Brexit divorce bill until the EU offers better terms.
Jeremy Hunt, considered another leading contender, claimed Angela Merkel indicated the EU would be willing to renegotiate the existing deal if a new prime minister had the "right approach".
The EU has repeatedly ruled out the prospect of reopening the withdrawal agreement - although stressed they are open to further discussions on the 'future relationship'.
Speaking in the Dáil today, Mr Varadkar said Theresa May was not a bad negotiator and got a good deal from Europe.
The Taoiseach warned British politicians not to think a better deal is in the offing.
He suggested: "I'm a little bit concerned that some people in London seem to think because the House of Commons failed to ratify the agreement then that automatically means they're going to get a better one.
"That is a terrible political miscalculation, and I hope that is not the one being made across the water."
He added that any belief the UK will get a better deal would also "really misunderstand how the European Union works".
Also speaking in the Dáil earlier, Fianna Fáil leader Micheál Martin said the Tory leadership contest is 'depressing'.
He observed: "Now that we know the positions of a number of the contenders, it is especially depressing that many of the candidates seem to have no interest in, or feel for, Northern Ireland or the Republic of Ireland."
