Prime Minister Theresa May on Thursday faced strong opposition in parliament after Britain and the EU came to an agreement on the outlines of post-Brexit relations as part of a draft deal due to be signed off by EU leaders.

After briefing her cabinet in a teleconference call, May addressed the House of Commons, saying it was the “best possible deal.”

EU Council President Donald Tusk said the 26-page declaration encompassing issues including trade, security and the environment was agreed “in principle” and would be sent to the other 27 member states for approval.

The pound rose by about 1% against the dollar and also strengthened against the euro on the news, which assuaged fears that the UK could leave the EU next March without new arrangements in place.

However, the agreement does not address the issues of fishing rights and Gibraltar, which have raised serious concerns in EU capitals.

After the draft declaration was agreed on Thursday, Spanish Prime Minister Pedro Sanchez repeated a threat to scupper the deal if Madrid’s concerns about Gibraltar are not addressed.

Also, the deal could still be rejected by the British parliament.

British MPs of all parties criticized the divorce agreement announced last week, which includes a financial settlement and a controversial plan to avoid a hard Irish border.

– With reporting from Agence France-Presse