Faced with almost certain rejection, U.K. Prime Minister Theresa May delayed a parliamentary vote on Monday on her plans for leaving the EU. To win over MPs, she is now seeking to amend the deal, in particular the complex arrangements concerning the future of the border between the U.K. and Ireland — the only land border between the U.K. and the rest of the EU.

The big picture: EU leaders have made clear that the 585-page withdrawal agreement cannot be changed. All May can expect is a side letter containing a legally meaningless “clarification,” which will satisfy very few, if any, MPs in London. Whenever she calls the vote, she is likely to face a heavy parliamentary defeat.

Background: The U.K. Parliament voted to leave the EU on March 29, 2019. Without a deal, the prospects for the U.K.’s — and, to some extent, the EU’s — economy will darken. The government’s own projection is that a “no deal” Brexit could provoke an economic slump of 10%.

  • A whole range of connections, developed over almost half a century, will be severed. Trade will be disrupted. Cooperation on fighting crime and terrorism (depending on shared databases) will be weakened. The U.K. will find it harder to obtain vital medicines. The future of U.K. citizens living in the EU, and EU citizens in the U.K., will be thrown into question.

What's next: The pressure to prevent a “no deal” Brexit will be intense. There are several possible paths:

  1. May might quit and be succeeded by a new prime minister who reopens talks with the EU.
  2. The government might fall, triggering a fresh general election. This looks unlikely at present, as there is no majority in Parliament to bring down the government, which could clear the way for the left-wing Labour party led by Jeremy Corbyn to take power.
  3. Parliament might vote for a new referendum to ask voters whether they really want to leave the EU after all. Support for a “People’s Vote” is rising at Westminster as the least bad way out of the present crisis.

The bottom line: None of the three options can realistically be concluded by March 29. The U.K. looks certain to remain in the EU at least into the summer — and, very possibly, indefinitely.