Theresa May used a European Union meeting in Bulgaria to seek assurances that the bloc will accept U.K. proposals to prevent a hard Irish border. She didn’t get the guarantees she wanted.

In an unexpected move to kick-start talks that have been stalled since March, the U.K. prime minister pitched her latest plans for post-Brexit customs ties to German Chancellor Angela Merkel, French President Emmanuel Macron and other leaders gathered in Sofia.

May was eager to find out what sort of response she can expect when EU leaders assess progress on the Irish border issue at their summit in June, a senior EU official said, asking not to be named because the discussions were private. EU President Donald Tusk told her that it was too early to give any assurances because of the “disorientating” messages the EU was getting from London, the official said.

The official declined to give any details of May’s proposals. But Irish Prime Minister Leo Varadkar indicated she was suggesting some form of close alignment with the EU customs regime without actual membership. Her plan might solve “a lot of problems,” but not all issues connected to the single market, he said.

For May, the plan, which still hasn’t been formally announced, has risks. Keeping EU rules for longer could enrage Brexit supporters, and even prompt them to try to oust her. Her spokeswoman, Alison Donnelly, said that than the plan was a “fallback” and that May’s government neither expects nor wants it to come to pass.

Another Concession

May has insisted the U.K. will be leaving the EU customs union after Brexit and has rejected the EU’s suggestion that Northern Ireland remain inside the bloc in order to maintain trade flows with the Irish Republic to the south. EU officials had previously expressed skepticism about the government’s latest ideas.

The U.K. said on Thursday that it will make a formal proposal for post-Brexit customs arrangements soon. It needs to win the EU’s approval if there’s going to be an overall Brexit deal before the U.K. leaves the bloc in 10 months’ time.

Applying the EU tariff regime across the whole of the U.K.—if that is what she has in mind—would be a major concession from May, potentially limiting her scope for striking free trade deals with countries outside the bloc. It could be a concession too far for euroskeptics, who could trigger a leadership challenge.

But getting the EU onside early, particularly if it paved the way for British gains in other areas, might give her some leverage with pro-Brexit lawmakers who think the U.K. has already given in too much to Brussels.

Full Team

In a sign of her determination to inject fresh impetus into the process, May brought chief Brexit negotiator Olly Robbins, chief of staff Gavin Barwell and her principal private secretary Peter Hill to her meeting in Sofia with Tusk and European Commission President Jean-Claude Juncker.

“The leaders discussed the positive progress which had been made in the talks so far,” a spokeswoman for May said in London. Another spokesman said he wouldn’t comment on the EU’s description of the meetings.

The EU official said that May wanted to offer the EU assurances that her plan would be ready by June and that it would unblock the issue. Leaders stressed that they needed to see the detail written down before they could give the positive response she was looking for, the official added.

“What was described to us was described verbally and conceptually,” Varadkar said. “I’d certainly like to see it written down in black and white.”