LONDON - British Prime Minister Theresa May will fly to a European Union summit in Brussels on Thursday (March 22) to seek the expected support of fellow heads of government for an interim deal to extend the period Britain has to negotiate Brexit terms.
This, Mrs May hopes, should grant businesses greater trading predictability, and diplomats a breathing space to continue the complicated task of separating Britain from the EU.
But Mr Donald Tusk, the president of the European Council - the European body which includes all EU heads of states and governments - has warned there are "no guarantees" that the deal will be approved until the objections of "some of the most concerned member states" of the EU are addressed.
Meanwhile back home, Theresa May is under fire from her own backbench MPs for making too many concessions.
Under existing treaty arrangements, Britain would have had until the end of March next year to leave the EU - regardless of whether an agreement is in place to govern future economic and political relations with the continent.
Diplomats in London and Brussels agree that such a timeframe is hopelessly short to forge a deal for which there is no precedent and, since the only alternative is for Britain to crash out of the EU with no arrangement in place and with potentially catastrophic consequences for everyone, an interim agreement giving negotiators more time is inevitable.
The deal before the EU leaders represents an awkward compromise. It extends the deadline Britain has to negotiate its departure to the end of 2020 and until then, the British will retain all the benefits of the current European single market, a clear European concession.
But Britain agrees in turn that this means it would be expected to apply all new EU laws and regulations adopted between now and then, even though Britain would have no say in how these are drafted.
The remaining 27 EU member-states dropped a demand that Britain should not negotiate free trade agreements with countries outside Europe until it physically leaves the EU, meaning British diplomats would be able to start such negotiations.
However, any free trade deals London signs with the rest of the world will not come into force until early 2021, thereby upholding the principle that everything remains subordinated to final arrangements with Europe.
Mr David Davis, the British minister responsible for Brexit, hailed this 129-page interim agreement as a "significant moment", giving business and citizens "the reassurances they demanded". But politicians on both sides of the waters separating the UK from Europe are not so enthusiastic.
Government backbenchers in London are furious with Mrs May for accepting that not only would EU citizens continue to be free to work in Britain until 2020, but that all those who do so will also be entitled to stay on for as long as they wish after the Brexit deadline, and bring in their immediate families.
Opponents claim that this betrays Mrs May's initial promise to "take back control of Britain's borders".
Mr Nigel Farage,founder of the UK Independence Party, a far-right, anti-immigrant movement, promptly dismissed Mrs May as "Theresa the Appeaser", thundering: "After vaunting her so-called red lines, she quickly rubs them out under EU pressure."
Meanwhile, Scottish politicians bemoan the fact that Britain's fish stocks will continue to be shared with the rest of the EU until the end of 2020. The issue may play into the hands of Scottish separatists who can now claim with some plausibility that the government in London has betrayed Scotland's interests. "There is no spinning this as a good outcome", said Mr Douglas Ross, a Scottish MP from Mrs May's ruling Conservative Party.
Some European governments are not keen on the interim deal either. Spain claims that the arrangements do not apply to Gibraltar, a British colony which the Spanish claim as their own territory.
And Ireland continues to demand special arrangements for Northern Ireland, which remains part of the United Kingdom but has to retain close trade ties with the rest of the island if it is not to experience massive trade disruptions.
After a period of further haggling, the deal is still expected to be approved by the time EU leaders conclude their summit on Friday. But the entire discussion serves as a grim reminder of just how complicated the Brexit negotiations remain; two years after the people of Britain narrowly voted to leave the EU, the only agreement currently on the table merely promises further negotiations, and hardly on Britain's terms.