The European Union won’t allow U.K. Prime Minister Theresa May to reopen negotiations over the Brexit divorce deal, officials said.

While the EU is prepared to add wording to the effect it has no wish to force the U.K. into a never-ending “backstop” arrangement in the absence of a broader trade deal, there’s little chance of wholesale changes. That commitment also wouldn’t be legally binding, according to the officials, who spoke on condition of anonymity citing the sensitivity of the matter.

In effect that means that the message from EU leaders, who hold a summit in Brussels this week, won’t be dramatically different from the one they gave when they signed the deal off last month: there’s no other version available. They’re also likely to call for preparations to be accelerated in case the U.K. crashes out of the bloc without an agreement.

“We will not renegotiate,” European Commission Mina Andreeva told reporters in Brussels on Monday. “Our position has therefore not changed.”

The EU already believes that it has made concessions on the backstop arrangement -- designed to prevent a hard border in Ireland -- during the negotiations, including by making it U.K.-wide rather than Northern Ireland-specific and by allowing a longer transition period to delay its taking effect.

May is calling off a crucial vote in Parliament on whether to approve her Brexit deal and told her cabinet she will head back to Brussels to seek a better offer from the European Union.

Brexit is currently not officially on the agenda of the summit on Thursday and Friday, but that’s likely to change with May's decision to call off the vote.

For the past two years, national governments have largely put the Brexit negotiations in the hands of the European Commission. But with less than four months before the U.K. is due to leave the EU, they may decide now is the time to take on a more hands-on role, one of the officials said.

Another official said the political declaration -- the part of the Brexit deal that isn’t legally binding -- could be revised, but that changing the backstop arrangement itself would be a “step too far.”

Earlier, Irish Prime Minister Leo Varadkar said the EU could clarify what’s in the withdrawal agreement but the substance of the deal will not be changed.