Irish Prime Minister Leo Varadkar (R) and EU Brexit chief negotiator Michel Barnier take part in a joint press conference in Dublin on April 8, 2019. | Paul Faith/AFP via Getty Images EU ready to negotiate customs union with UK, says Michel Barnier EU’s chief Brexit negotiator says the bloc could ‘quickly’ amend the declaration on the future relationship with the UK.

The EU is ready to discuss a post-Brexit customs union with the United Kingdom, the bloc's chief negotiator, Michael Barnier, said Monday.

Barnier was in Dublin to meet with Irish Prime Minister Leo Varadkar ahead of a crucial summit on Wednesday in Brussels, where EU27 leaders will consider a further delay to the U.K.'s departure deadline.

Appearing with Varadkar after their meeting, Barnier told reporters that if talks between U.K. Prime Minister Theresa May and opposition Labour leader Jeremy Corbyn yield an agreement to seek a customs union with the EU, Brussels is ready to work "quickly" toward that goal.

"We all hope that these talks will produce a positive outcome," Barnier said on the cross-party discussions currently underway in London.

"I have said many times before that we can be more — much more —ambitious in our future relationship with the U.K. The Political Declaration provides for a range of outcomes including a customs union. We are ready to make this clear if it helps and this work can be done extremely quickly," he continued.

Some EU leaders, notably French President Emmanuel Macron, have expressed reservations — if not outright reluctance — to granting the U.K. another extension to the deadline without greater clarity from London about how such a delay would help yield a consensus in London.

Varadkar, standing beside Barnier, said that Ireland is prepared to be patient.

"I sincerely hope that it will be possible to build a sufficient consensus in Westminster to enable ratification of the Withdrawal Agreement and an orderly Brexit thereafter," the Irish leader said.

"From Ireland's perspective, we are open to extending the deadline to allow time for these discussions to run their course and come to a conclusion. Above all, we want the Withdrawal Agreement to be ratified so negotiations can begin on the future relationship."

Council President Donald Tusk has proposed a one-year flexible extension of the deadline, which would allow the U.K. time to work out a Brexit plan with the option to leave the EU as soon as it is ready.

Varadkar's remarks underscore just how big a political risk it would be for Macron or any of the other 26 leaders to force a no-deal scenario with potentially catastrophic economic consequences while the talks in London still leave a prospect for a deal.

EU27 leaders have made a habit of demonstrating solidarity with Ireland ahead of any major meeting on Brexit. Barnier's visit on Monday maintained that practice.

Barnier said that he and Varadkar also discussed the potential consequences of a no-deal result for Ireland, and he reiterated a warning that the EU would refuse to negotiate any trade agreement with the U.K. following a no-deal departure unless and until there was agreement with Britain on three core issues: the Irish border, citizens' rights and a settlement of the U.K.'s financial obligations to the EU.

"Our goal is to protect the Good Friday Agreement, peace on this island, and the integrity of the single market," Barnier said. "It is not an easy task but I am confident we will find operational solutions."

He continued: "If the U.K. were to leave the EU without a deal, let me be very, very clear, we would not discuss anything with the U.K. until there is an agreement for Ireland and Northern Ireland, as well as for citizens' rights and the financial settlement."