BRUSSELS (AP) — European Union leaders are underlining that their divorce agreement with Britain cannot be renegotiated regardless of who becomes the next prime minister there.

At a summit of EU leaders Friday, Luxembourg Prime Minister Xavier Bettel said the current Brexit agreement “is the best possible deal.”

With Boris Johnson favorite to become next prime minister, Bettel says it makes no difference who takes office.

He says “it’s not possible (that) because you change the leader in the U.K. that we need to postpone decisions.”

EU leaders are due later Friday to briefly discuss political developments in Britain, which is set to leave the bloc on Oct. 31.

Some leaders say a new Brexit extension should only be granted to hold fresh elections or a new Brexit referendum.