Theresa May's Brexit deal has been rejected in a meaningful vote in the House of Commons.
The deal was defeated by a majority of 149, with 391 voting against the withdrawal agreement, and 242 voting in favour.
Among those who voted against the deal were 75 Conservative MPs and the entirety of the Independent Group.
Following the result of the vote, the Prime Minister said she "profoundly regrets" the decision MPs have taken.
"The best outcome is that the UK leaves the EU in an orderly fashion with a deal, and that the deal we have negotiated is the best and only deal available," she told the Commons.
As a consequence of the result, MPs will vote on whether or not they would support a no-deal Brexit tomorrow.
The Brexit secretary has told the House of Commons voting for the Prime Minister's withdrawal agreement will "extinguish the risk" of a no-deal Brexit.
In a last minute attempt to garner support for the deal, Stephen Barclay said voting in favour of it would allow the country to "move forward".
Boris Johnson speaking in the House of Commons
Boris Johnson has said leaving without a deal on March 29 was the only way for the country to retain its "self respect".
Speaking in the Commons today, the former foreign secretary said the changes secured by the Prime Minister were an "apron of fig leaves that does nothing to conceal the embarassment and indignity of the UK."
He acknowledged that leaving without a deal would be "the more difficult road" but added that it was "the only safe route out of the abyss and the only safe path to self respect."
Jeremy Corbyn slammed the Prime Minister for not achieving a “single change” to the withdrawal agreement.
Speaking in the Commons, the Labour leader said the Prime Minister had done nothing more than “slain the enormous paper tiger” she had constructed herself.
He added: “We are back again in the realm of smoke and mirrors: the illusion of changes when nothing in fact has changed.”
The Labour leader added that, in the unlikely event the bill would pass today, Labour would call for a confirmatory vote to be put to the public.
Theresa May during negotiations in Strasbourg, France
Speaking earlier, the Prime Minister said that Brexit “could be lost” if MPs do not back her deal during this evening’s meaningful vote.
Speaking in the House of Commons, Theresa May defended her withdrawal agreement.
She said: “The danger for those of us who want to deliver on the public’s vote for Brexit is that if this deal is not passed tonight, then Brexit could be lost.”
Prominent ERG member Jacob Rees-Mogg
The Leave-backing European Research Group has recommended MPs do not back Theresa May's Brexit deal.
Their so-called Star Chamber has determined that the government's new Brexit agreement does not meet the tests set for it.
The DUP has also said it does not believe the Prime Minister has made "sufficient progress" with the Brexit negotiations.
A DUP spokesman said: "We want to see a deal which works for every part of the United Kingdom. We will support the right deal which respects the referendum result and Northern Ireland's place as an integral part of the United Kingdom."
Geoffrey Cox gives a statement in the House of Commons
Theresa May's last-minute Brexit agreements "reduce the risk" that the UK could be trapped indefinitely in the backstop, but do not remove it altogether, the Attorney General told the House of Commons.
In his legal advice issued to the Prime Minister at around 11.30am this morning, Mr Cox said that the “legal risk remains unchanged” despite the Prime Minister's “legally binding” changes to the Irish backstop.
In his statement to the Commons on his legal advice, Mr Cox said: "The question for the House is whether in the light of these improvements, as a political judgment, the House should now enter into those arrangements."
What happened last night?
Theresa May with European Commission president Jean Claude-Juncker
On Monday night the Prime Minister said that she has secured “legally binding” changes to the Brexit deal, which ensure the Irish backstop cannot be permanent.
Following last-minute talks in Strasbourg ahead of the vote today, Mrs May has said she “passionately believed” her Brexit deal addressed concerns raised by MPs who feared the backstop would keep the UK in a customs arrangement with the EU indefinitely.
At a joint press conference with European Commission president Jean-Claude Juncker, Mrs May said the three new documents agreed provided the legal assurances critics of her stance had called for.
The Prime Minister said: "What we have secured is very clearly that the backstop cannot be indefinite. Cannot become permanent. It is only temporary. If it is the case that we were ever to get into the backstop.
"The legal instrument that we have agreed is an addition to the Withdrawal Agreement. It has the same legal status as the Withdrawal Agreement. It is legally binding.
"That is what Parliament asked us to secure and that is what we have secured."