British Prime Minister Theresa May is to hold last-minute talks with European Commission President Jean-Claude Juncker and European Council President Donald Tusk on the eve of an EU summit that was threatened by Spanish objections to her deal on Britain's withdrawal from the bloc.
Spain had threatened to veto the deal unless the wording was changed to give Madrid guarantees that it alone can decide on the future of the disputed territory of Gibraltar in direct talks with London.
However, an agreement reached on Saturday between Spain, the EU and Britain removed obstacles to the summit, both sides said.
"We have reached an agreement on Gibraltar," Sanchez said. He said any future decisions about Gibraltar would be taken only with Spain's consent.
May hopes to leave Brussels on Sunday with the terms of British withdrawal on March 29 and a comprehensive concept for future Britain-EU relations settled with the bloc.
Northern Irish opposition
The British premier is, however, also facing opposition closer to home, with the Democratic Union Party (DUP) of Northern Ireland, whose support is vital to her government, holding a conference on Saturday.
The right-wing and "Christian fundamentalist" DUP, which is in favor of Brtish rule in Northern Ireland, believes that the deal's backstop provision to ensure an open border on the island of Irelandwill give the province a different economic status compared with the mainland.
This, it fears, could increase the chances of Irish unification, which it vigorously rejects.
Getting the DUP on board will be highly important to May if the deal is to be passed by the British Parliament, where May's Conservative Party only has a minority. The Conservatives have a "confidence-and-supply" arrangement with the DUP's 10 members of parliament, allowing them an effective majority.
DUP leader Arlene Foster opposes the deal but has so far not totally withdrawn support for May
No-deal warning
The expected presence of Britain's finance minister, Philip Hammond, at Saturday's conference underlines the central role the highly conservative party now plays.
Hammond on Saturday reiterated his support for May's draft deal on Saturday, telling broadcaster BBC that it was "a way of Britain leaving the European Union ... with minimum negative impact on our economy."
At the same time, he warned that no deal would mean "very serious" consequences in the future for the economy, jobs and prosperity.
The conference will also be attended by former Foreign Secretary Boris Johnson, a vehement critic of the deal, and Fabian Picardo, the chief minister of Gibraltar.
