U.K. Prime Minister Theresa May has begun briefing her Cabinet on the text of the almost-complete Brexit deal, as her negotiators seek to finalize the last outstanding issue in Brussels.

Senior ministers have been invited into a private reading room in a building adjoining May’s offices to examine the 95 percent of the withdrawal package that’s been agreed so far, according to people familiar with the matter.

What’s missing is the most contentious part of the deal — the guarantee to keep goods trade flowing freely across the Irish border. Options are now being negotiated in detail by British and European officials in Brussels, according to people familiar with the positions of both sides.

If these talks are successful, officials will declare that “decisive progress” has been made on the terms of the U.K.’s exit from the bloc. British officials say this could happen next week or even as early as Thursday.

May will still need to get the deal, including the so-called Irish border backstop plan, approved by her Cabinet and later by Parliament — where she’s likely to face considerable opposition.

But two people familiar with the issue suggested she would not need to wait for Cabinet approval before signing up in principle to the terms negotiated in Brussels.

There was no agreement at a Cabinet meeting on Tuesday as ministers were still discussing a fix for the Irish border issue. They expect another meeting to be called within days, when May is likely to press them to sign off on her deal.

She still faces one major hurdle to getting that Cabinet agreement. Pro-Brexit ministers led by Environment Secretary Michael Gove are demanding to see the full legal advice on which May’s plans are based.

Gove and his euroskeptic Cabinet colleagues are concerned May will tie the U.K. into an open-ended customs union with the EU — all as part of the backstop plan for the Irish border. Pro-Brexit members of May’s Tory party will see that as a betrayal of the U.K.’s 2016 vote to leave the EU, and could try to block the Brexit deal and even attempt to oust her.