LONDON — Prime Minister Boris Johnson suffered a stinging defeat Saturday as Parliament rebuffed his campaign to take Britain out of the European Union by the end of the month and forced him to seek an extension that he had vowed never to pursue.
The turbulent events left Johnson’s agreement in limbo and threw British politics once again into chaos, with any number of outcomes possible: a no-deal exit from the EU, a second referendum on whether to leave at all, or a general election that could shift the balance in Parliament. The only sure result was continuing frustration and confusion among the British public.
Late Saturday night, Johnson formally applied to the EU, in an unsigned letter, for another extension of Britain’s departure, something he said he would rather be “dead in a ditch” than do.
Johnson sent a separate signed letter to the president of the European council, Donald Tusk, in which he said a “further extension would damage the interests of the U.K. and our EU partners, and the relationship between us.”
The conflicting letters left it to the EU to decide how to respond to Johnson. Most analysts expected it would grant an extension, although that was unlikely to clarify the muddled situation in London.
It capped a dramatic day of legislative maneuvering in which lawmakers debated Johnson’s deal while enormous crowds of anti-Brexit protesters marched outside Parliament, Johnson implored lawmakers to approve the agreement, which would pave the way for Britain to leave the EU at the end of the month.
The prime minister argued that it was the best deal Britain could hope to strike — one that, in his telling, would position the country for a thriving future as an agile free agent in the global economy — and that any further delay would be “pointless, expensive and deeply corrosive of public trust.”
Instead, by a vote of 322-306, lawmakers passed a last-minute amendment, brought by Oliver Letwin, an expelled member of Johnson’s Conservative Party, that would delay final approval on the agreement until after Parliament passes the detailed legislation to enact it.
A defiant Johnson said he would push for another vote on his agreement early in the coming week. But that could present opponents with an opportunity to try to amend his plan.
“I’m not daunted or dismayed by this particular result,” Johnson said.
Still, it was a stinging setback for the prime minister — and as with his previous defeats in Parliament, one that came at the hands of a former member of his own party.
Letwin, a veteran Conservative lawmaker, was purged from the party last month for supporting a law intended to prevent Britain from leaving the EU without any agreement, which many see as risking a disorderly, economically damaging rupture.
Letwin, who supports Johnson’s Brexit deal, argued that the amendment was simply a safety net to prevent pro-Brexit hard-liners from sabotaging the implementing legislation and, in the ensuing political vacuum before the Oct. 31 deadline, engineering the no-deal rupture that some want.
Yet some opponents of Johnson’s Brexit deal supported the Letwin amendment, too — in hopes that further delays might open the door to other options.
For the prime minister, who has staked his claim to No. 10 Downing St. on delivering the withdrawal, the amendment was another in a series of setbacks in Parliament, preventing him from forcing lawmakers into a binary decision on whether to support his plan.
Assuming that Johnson does request another Brexit extension, the EU would have to decide whether to grant a delay of a few more weeks to resolve the technical details or a longer delay to allow a general election or perhaps a second referendum.
Meeting on a Saturday for the first time since the Falklands War in 1982, members of the House of Commons rose, one after the other, to fervently endorse or reject Johnson’s deal. The debate seemed to be ultimately less about the details of the plan, with its fiendishly complicated arrangements for trade with Northern Ireland, which is part of the United Kingdom, than about whether Britain could finally put Brexit behind it.
Opponents of the plan accused Johnson of negotiating a shoddy deal that would leave a post-Brexit Britain vulnerable to predatory trade deals with other countries, not least the United States.
“This deal would inevitably lead to a Trump trade deal, forcing the UK to diverge from the highest standards and expose our families to chlorine-washed chicken and hormone-treated beef,” said the leader of the opposition Labour Party, Jeremy Corbyn, referring to fears of chemically treated imports from the United States.
For Johnson, 55, a flamboyant politician and former mayor of London who has been in office since July, it was a crucial moment. He spoke with a tone of gravity and conciliation that contrasted starkly with the inflammatory language he has used during previous parliamentary debates over Brexit.
Johnson’s deal differs from those of his predecessor, Theresa May, primarily in its treatment of Northern Ireland. Needing to avoid physical border checks, May opted to keep the entire United Kingdom in the EU’s customs union, which was unacceptable to hard-line Brexiteers. Johnson sought to satisfy them by keeping Northern Ireland subject to the bloc’s rules in a practical sense but legally outside it with the rest of Britain.
His deal is at the extreme end of divorce settlements that Britain could have negotiated with the EU. It commits the country to very little alignment with the bloc on trade or regulations, turning its back on much of the web of rules that critics in Britain consider stifling or a threat to their sovereignty.
By keeping the EU at arm’s length, Johnson and his lieutenants contend, Britain can set out to transform itself into an agile, lightly regulated competitor in the global economy — or “Singapore-on-Thames,” to use a phrase coined by Brexit evangelists.
To do that, however, Britain must first negotiate new trade agreements with dozens of parties, including the EU and the United States, a painstaking process that could take several years. And Johnson’s plan allows for only a transitional period ending in 14 months, although this could be extended for a maximum of two years.