Here is an abridged text of her speech:
“I became Prime Minister almost three years ago – immediately after the British people voted to leave the European Union. My aim was – and is – to deliver Brexit and help our country move beyond the division of the referendum and into a better future.
I knew that delivering Brexit was not going to be simple or straightforward. The result in 2016 was decisive, but it was close.
The challenge of taking Brexit from the simplicity of the choice on the ballot paper to the complexity of resetting the country’s relationship with 27 of its nearest neighbours was always going to be huge.
While it has proved even harder than I anticipated, I continue to believe that the best way to make a success of Brexit is to negotiate a good exit deal with the EU as the basis of a new deep and special partnership for the future.
That was my pitch to be leader of the Conservative Party and Prime Minister. That is what I set out in my Lancaster House speech and that was what my Party’s election manifesto said in 2017.
That is in essence what the Labour Party’s election manifesto stated too and over 80% of the electorate backed parties which stood to deliver Brexit by leaving with a deal.
We have worked hard to deliver that – but we have not yet managed it.
I have tried everything I possibly can to find a way through.
It is true that initially I wanted to achieve this predominantly on the back of Conservative and DUP votes. In our Parliamentary system, that is simply how you normally get things done.
I sought the changes MPs demanded. I offered to give up the job I love earlier than I would like.
And on 29th March – the day we were meant to leave the EU – if just 30 MPs had voted differently we would have passed the Withdrawal Agreement. And we would be leaving the EU.
But it was not enough. So I took the difficult decision to try to reach a cross-party deal on Brexit.
Many MPs on both sides were unsettled by this. But I believe it was the right thing to do. We engaged in six weeks of serious talks with the Opposition, offering to compromise.
But in the end those talks were not enough for Labour to reach an agreement with us. But I do not think that means we should give up.
ONE LAST CHANCE
The House of Commons voted to trigger Article 50 and the majority of MPs say they want to deliver the result of the referendum. So I think we need to help them find a way and I believe there is now one last chance to do that.
I have listened to concerns from across the political spectrum. I have done all I can to address them.
And today I am making a serious offer to MPs across Parliament – a new Brexit deal.
As part of that deal I will continue to make the case for the Conservative Party to be united behind a policy that can deliver Brexit.
Nine out of 10 Conservative MPs have already given the Withdrawal Agreement their backing and I want to reach out to every single one of my colleagues to make the very best offer I can to them.
We came together around an amendment from Sir Graham Brady – and this gave rise to the work on Alternative Arrangements to the backstop. Although it is not possible for those to replace the backstop in the Withdrawal Agreement, we can start the work now to ensure they are a viable alternative.
NORTHERN IRISH BACKSTOP
So as part of the new Brexit deal we will place the government under a legal obligation to seek to conclude Alternative Arrangements by December 2020 so that we can avoid any need for the backstop coming into force.
I have also listened to Unionist concerns about the backstop so the new Brexit deal goes further to address these.
It will commit that, should the backstop come into force, the government will ensure that Great Britain will stay aligned with Northern Ireland.
We will prohibit the proposal that a future government could split Northern Ireland off from the UK’s customs territory and we will deliver on our commitments to Northern Ireland in the December 2017 Joint Report in full.
We will implement paragraph 50 of the Joint Report in law. The Northern Ireland Assembly and Executive will have to give their consent on a cross-community basis for new regulations which are added to the backstop.
And we will work with our (DUP) Confidence and Supply Partners on how these commitments should be entrenched in law.
This new Brexit deal contains significant further changes to protect the economic and constitutional integrity of the United Kingdom and deliver Brexit.
It is a bespoke solution that answers the unique concerns of all parts of the community in Northern Ireland.
But the reality is that after three attempts to secure parliamentary agreement, we will not leave the European Union unless we have a deal that can command wider cross-party support.
That’s why I sat down with the Opposition. I have been serious about listening to views across the House throughout this process.
That is why when two Labour MPs, Lisa Nandy and Gareth Snell, put forward their proposals to give parliament a bigger say in the next phase of the negotiations I listened to them.
So the new Brexit deal will set out in law that the House of Commons will approve the UK’s objectives for the negotiations on our future relationship with the EU and they will approve the treaties governing that relationship before the Government signs them.
And while the talks with the opposition did not reach a comprehensive agreement, we did make significant progress in a number of areas.
Like on workers’ rights. I am absolutely committed to the UK continuing to lead the way on this issue. But I understand people want guarantees. And I am happy to give them so the new Brexit deal will offer new safeguards to ensure these standards are always met.
We will introduce a new Workers’ Rights Bill to ensure UK workers enjoy rights that are every bit as good as, or better than, those provided for by EU rules.
And we will discuss further amendments with trade unions and business.
ENVIRONMENT AND TRADE
The new Brexit deal will also guarantee there will be no change in the level of environmental protection when we leave the EU. And we will establish a new independent Office of Environmental Protection to uphold the highest environmental standards and enforce compliance.
The new Brexit deal will also place a legal duty on the government to seek as close to frictionless trade with the EU in goods as possible, subject to being outside the Single Market and ending freedom of movement.
In order to deliver this, the UK will maintain common rules with the EU for goods and agri-food products that are relevant to checks at the border. This will be particularly important for our manufacturing firms and trade unions, protecting thousands of jobs that depend on just-in-time supply chains.
The most difficult area is the question of customs.
At the heart of delivering Brexit lies a tension between the strength of our ambition to seize the new opportunities that Brexit presents – and the need to protect the jobs and prosperity that are built on an interconnected relationship with other European economies.
This ambition should not be divisive. There are many people who voted to leave who also want to retain close trading links with Europe. Just as there are many people – like myself – who voted to remain and yet are excited by the new opportunities that Brexit presents.
Indeed I believe that one of the great opportunities of leaving the European Union is the ability to have an independent trade policy and to benefit from the new jobs and industries that can result from deepening our trade ties with partners across every continent of the world.
But I have never believed that this should come at the expense of the jobs and livelihoods that are sustained by our existing trade with the EU.
And to protect these, both the government and the opposition agree that we must have as close as possible to frictionless trade at the UK-EU border.
Now the government has already put a proposal which delivers the benefits of a customs union but with the ability for the UK to determine its own trade and development policy.
Labour are both sceptical of our ability to negotiate that and don’t believe an independent trade policy is in the national interest. They would prefer a comprehensive customs union – with a UK say in EU trade policy but with the EU negotiating on our behalf.
If we are going to pass the Withdrawal Agreement Bill and deliver Brexit, we must resolve this difference.
As part of the cross-party discussions the government offered a compromise option of a temporary customs union on goods only, including a UK say in relevant EU trade policy and an ability to change the arrangement, so a future government could move it in its preferred direction.
We were not able to agree this as part of our cross-party talks – so it is right that parliament should have the opportunity to resolve this during the passage of the Bill and decide between the government’s proposal and a compromise option.
And so the government will commit in law to let Parliament decide this issue, and to reflect the outcome of this process in legislation.
I have also listened carefully to those who have been arguing for a Second Referendum.
I have made my own view clear on this many times. I do not believe this is a route that we should take, because I think we should be implementing the result of the first referendum, not asking the British people to vote in a second one.
But I recognise the genuine and sincere strength of feeling across the House on this important issue.
The government will therefore include in the Withdrawal Agreement Bill at introduction a requirement to vote on whether to hold a second referendum. This must take place before the Withdrawal Agreement can be ratified.
And if the House of Commons were to vote for a referendum, it would be requiring the government to make provisions for such a referendum – including legislation if it wanted to ratify the Withdrawal Agreement.
So to those MPs who want a second referendum to confirm the deal: you need a deal and therefore a Withdrawal Agreement Bill to make it happen. So let it have its Second Reading and then make your case to Parliament.
Finally, we cannot expect MPs to vote on the same two documents they previously rejected. So we will seek changes to the political declaration to reflect this new deal.
Reporting by Stephen Addison; editing by Costas Pitas