BRUSSELS (Reuters) - Theresa May has got nowhere with the EU in seeking an early guarantee of post-Brexit rights for British and European expatriates, officials said on Friday after the British prime minister pushed the issue again at an EU summit.

Britain's Prime Minister Theresa May leaves a EU Summit in Brussels, Belgium December 15, 2016. REUTERS/Yves Herman

“We cannot now do some deal quickly with her,” said one person familiar with some of May’s discussions in Brussels on Thursday. “This simply won’t work. It has to be part of a whole process.”

May briefed the summit on her plan to trigger the two-year withdrawal process by the end of March, whatever the outcome of a British Supreme Court case, officials who were present said.

She also repeated her wish to see uncertainties over the status of people living as foreigners on either side of the new UK-EU frontier settled early on. Irish Prime Minister Enda Kenny said none of the other 27 responded to that.

Summit chair Donald Tusk has said in recent weeks that May will get nowhere with such requests until she formally triggers talks under Article 50 of the EU treaty, and even then, promises will mean little until a comprehensive Brexit deal is agreed.

“Nothing will be agreed until everything is agreed, so it is hard to see what legal clarity people can be given on issues like residency rights before a final deal,” an EU official said.

However, another official involved in preparations for Brexit talks said expatriate citizens were unlikely to become “bargaining chips” between London and Brussels: “Both sides have big interests in avoiding that.”

EU FRICTIONS

May herself welcomed the fact that EU leaders had agreed on how they would organize themselves to negotiate, although in-fighting between Brussels institutions rumbled on Friday.

National leaders and the executive European Commission, whose Michel Barnier will be chief EU negotiator, tweaked their plan in order to allow the European Parliament to be present in some planning sessions for the negotiators.

But the lawmakers want a full negotiating role, and officials said the legislature, whose approval is needed for a Brexit accord, would keep pressing. Its president, Martin Schulz, warned on Thursday that the assembly could sink a deal.

A parliamentary official said Schulz, who is stepping down, feared that a chamber where party discipline is always weak would be particularly unbiddable when the Brexit deal is due for ratification, just as lawmakers campaign for re-election in May 2019.

But other officials said Commission President Jean-Claude Juncker was concerned that a proliferation of EU voices would weaken Barnier’s position. Some also fear that lawmakers might leak key elements of the EU’s negotiating strategy.