British Prime Minister Theresa May's Brexit deal was headed for defeat in a historic vote in parliament Tuesday, pitching Britain into the unknown just 17 days before it is scheduled to leave the European Union.
Parliament's failure to back the divorce terms could unleash economic chaos — it raises the risk of Britain severing ties with its biggest trade partner on March 29 without a deal after 46 years of EU membership.
May had dashed off to Strasbourg on Monday to wrest concessions from EU leaders in a last-gasp bid to win parliament's blessing in one of its most consequential votes in generations.
The British leader announced that she had secured the "legally binding changes" to the vexing issue of the Irish border that lawmakers had long sought.
But Attorney General Geoffrey Cox, who provides the government with independent legal advice, said the risk in the most contentious points of the 585-page withdrawal deal agreed with the EU "remains unchanged".
May's initial deal with Brussels on unwinding Britain's EU membership suffered an overwhelming defeat at the hands of MPs in January, with anti-Brexit MPs and hardliners forming an unlikely alliance.
The European Research Group of Brexit hardliners in May's Conservative Party and the Democratic Unionist Party (DUP), which gives May her working majority in parliament, both came out against the deal on Tuesday.
The main opposition Labour Party also opposes it.
The pound reversed the gains it had made after May's announcement on Monday and tumbled after Cox's advice was released.
'Nothing has really changed'
The so-called "backstop" solution for the Irish border — designed to avert sectarian violence from returning to Britain's Northern Ireland — is opposed by more ardent Brexit supporters.
They pressed May to secure the right for Britain to pull out of the arrangement or to make it time limited.
But Brussels has called it essential for preserving the bloc's external border after Brexit.
The DUP said in a statement that "sufficient progress has not been achieved at this time" and called for a "sensible deal".
The DUP's consent was seen as vital for swaying members of May's own party to soften their opposition and either back the deal or abstain in the vote.
But there was scant evidence of support for May's compromise in Conservative ranks.
"Nothing has really changed, and it is still a bad deal so unable to vote for this," Conservative MP Andrea Jenkyns tweeted.
'Brexit could be lost'
May warned lawmakers in a desperate last attempt to sway them that "Brexit could be lost" if they voted against her Tuesday.
"I think everybody needs to recognise, for those who genuinely want to deliver Brexit, that actually if this deal does not go through tonight, then this house risks no Brexit at all," May said.
Leaders across Europe also united behind a message that this was the best and final offer Britain could expect.
"There will be no third chance," European Commission chief Jean-Claude Juncker said after his talks on Monday with May.
And German Chancellor Angela Merkel said Tuesday that the EU was making "far-reaching proposals that take into account the concerns of Great Britain and to find answers for them".
No-deal and delay
Another defeat would tee up additional votes on the way ahead that May has promised in a bid to preserve unity inside her fractured government.
One on Wednesday would decide whether Britain should simply leave on March 29 without any deal at all.
That option is fraught with economic dangers and is backed only by hardcore proponents of the divorce.
The "no-deal" scenario's likely defeat would lead to a vote on Thursday on requesting a delay to Brexit from the EU.
The other 27 nations would need to back the extension unanimously and decide how long it should be. Their leaders will meet in Brussels for a summit on March 21-22.
But any postponement may have to be short-lived.
Juncker on Monday said a delay beyond European Parliament elections at the end of May would mean Britain would have to take part in the polls.
Britain is scheduled to leave the European Union on March 29. Leaving without a deal is expected to unleash economic chaos.