In recent months, I have spent time talking to business leaders in the UK and around the world. They all have two questions for me. Is there going to be a Brexit deal? Is there a chance that Jeremy Corbyn will become Prime Minister? My reply is always the same. That those two questions are inextricably linked.
If there is a sensible deal, then it is likely that the UK will enjoy an economic boost, releasing pent-up investment from a period of deep uncertainty. Businesses based here would stop sitting on their hands and commit to the new factories, warehouses and capital projects that we need. Investors abroad would once again feel confident that the UK was ‘open for business’, and would seek out the immense opportunities that we offer.
If this happens, the prospects of Corbyn being elected recede dramatically. Improving economic growth and confidence would facilitate continuing high levels of employment, wage growth and investment in public services. The Conservatives would secure their hard-won reputation for responsible government, fiscal prudence and effective management of the economy.
On the other hand, if there is not a deal, and a chaotic exit from the EU, the picture will change dramatically. Businesses will not only sit on their hands, but may start to withdraw activity from the UK. Investment from abroad may be replaced by dramatic divestment.
Now of course, over time things may settle down. But there will undoubtedly be a risk of serious economic dislocation – causing substantial job losses, slowing growth and curbing the ability to improve public services.
And of course, Corbyn and John McDonnell are desperate for that to happen – some kind of shock to the UK that can help to win them power.
Ideally, they want to force an early general election, because the Conservatives can’t agree on a plan.
Failing that, they would take a violent and disorderly departure from the EU, leading to a recession – and then to election victory at a later date.
Chaos and uncertainty are their route to power. This is more than ruthless ambition; it is rooted in ideology.
Karl Marx predicted the inevitable demise of capitalism as part of the great tide of history. Frustratingly for him, it never happened.
Living in England until the end of his life, he marvelled at the ability of the British to adapt their system to accommodate the needs and demands of their changing industrialised economy.
His theory did not predict the peaceful emergence of the NHS or the welfare state. He died miserably ruminating over his unfinished sequel to Das Kapital. The Marxists in Britain have been continually disappointed. They have lurked at the fringes of Labour politics for many years.
Unfortunately, they have now entered the mainstream. They are waiting to seize their moment to impose their already discredited ideology on generations who have not experienced its horrors first hand. It is the duty of the Conservative Party to stop this.
A Corbyn-led Labour Government would be a disaster for this country. And although Brexit is undoubtedly a seismic event, there is no need for it to lead to a tsunami, destroying all before it. The Conservative Party has faced momentous moments before. The reaction has always been pragmatism. Evolution not revolution. Steadiness and deal-making.
In her speech in Birmingham, Theresa May reminded us of this legacy. She asked her party to come together in the national interest to deliver a solution to the Brexit conundrum – to help her to thread the needle of respecting the democratic result of the referendum, of preserving our proud Union, of keeping the economy on track and business on side, and of finding a fair basis for trading with our close neighbours and allies.
We’re leaving the EU: the referendum result must be respected. As with all marriages, it may end with sour words and slamming doors. But once the anger has subsided, we need to come together to work out the future, to protect the interests of the next generation.
We need to be grown up enough to accept that although we are going through a divorce, we cannot just walk away from our responsibilities and move on. This can take time and involve ongoing obligations.
And as the Prime Minister reminded us, it is not just Conservatives who need to stand firm.
Our friends in the DUP know what a Corbyn government could mean. They know that his well-documented republican sympathies would risk the break-up of the Union.
He longs for a united Ireland with the same passion that he dislikes the United Kingdom.
So we need to make sure that we rally behind the Prime Minister and help her to deliver a sensible, measured deal.
We need to do this to frustrate Corbyn and McDonnell. We need to do this in the national interest. And we need to do this to keep Marx spinning in his grave up in Highgate.
• Andrew Feldman (Baron Feldman of Elstree) was chairman of the Conservative Party from May 2015 to July 2016, and before that was its co-chair from May 2010. This piece was first published overnight from Wednesday to Thursday on the website ConservativeHome