For fear of upsetting her cabinet, Theresa May has abandoned a major speech planned for next week that would have set out her intentions for the Brexit endgame. That is a risk she must take. Here is the speech she should be giving.

“I want to clearly set out where we stand on Brexit. Uncertainty has gone on too long. Businesses are desperate for guidance, and the country for leadership. It would be irresponsible of me to allow confusion to continue, simply because of internal disputes within my party. The United Kingdom is to leave the EU in March of next year, by the acknowledged wish of the British people. But the referendum was on whether to leave the EU, not how. On that we should be guided by parliament, our expert advisers and public opinion.

The referendum was on whether to leave the EU, not how. On that we should be guided by parliament

Both main parties have committed themselves to two, unhelpfully incompatible, goals. One is a rejection of “membership” of the single market, and of free movement of people. The other is retention of friction-free trade in a customs union. The latter is overwhelmingly the wish of business, the City of London, trade unions and tens of thousands of employers and workers in healthcare, construction, hospitality and agriculture.

I can see the appeal to some of my colleagues of a hard Brexit. It echoes Disraeli’s view of Britain as not”a mere European power … but a great maritime empire”.

A no-deal economy would, in my view, muddle through. But this is an extraordinary leap of faith, and one that will plainly impose costs across the economy. As a government we cannot ignore our economy’s need for some 2 million European migrant workers, or gamble with the livelihoods of millions of Britons who depend on their services. It was why I myself supported remain.

No responsible government can opt for short-term pain in the dream of long-term gain. Yes, world markets are expanding faster than Europe’s, but not remotely on a compensating scale. It is fantasy to imagine otherwise.

Public opinion is still divided on Brexit. It is not divided on retaining close trade links with Europe, which is supported by some 70%. There is no way we can achieve tariff-free or frictionless access to EU markets other than by accepting the disciplines of those markets. Links with the EU have grown close over 40 years of membership. I ask my colleagues to accept that there is no move among the British people to reverse them.

The overwhelming opinion of my advisers and those with whom we have been consulting this past year is that we should retain the existing tariff-free access. This is most simply achieved by being within the European Economic Area (EEA), the so-called Norway option. I know I have rejected the EEA in the past. But I now propose that we should treat it as the template for long-term negotiation, with a cross-party agreement to revisit it in 10 years. I am aware of its downside: we would lose a vote on, though not necessarily influence over, EU trade policy.

There remains the dominant issue of immigration. Polls show public concern is less about numbers than control. Many wish to restore some distinction between British residents and European newcomers in access to welfare, health and housing. I have pointed out to our European partners that many of them are tightening their borders, especially in the east. As for benefits, all EU countries have various restrictions on entitlements.

We must clarify EU citizens’ rights during transition. I accept that a transition, especially if it is to a longer-term EEA, should imply continuity of status. Even if we were to negotiate an opt-out from total freedom of movement, some form of temporary certification for EU citizens must be negotiable. We are leaving the EU, yet we are eager for EU employees.

My party took Britain into Europe in 1973. Our marriage to Europe has always been semi-detached, but never detached. In 2016 the British people agreed with millions of other Europeans – few of them consulted – that European union had gone too far. I believe our leaving should expedite much-needed reform.

To the opposition I make a plea. Taking this forward will be immeasurably easier with a united front. The nation is passing through its most seismic episode for half a century. When it is past, none of us may be sitting where we are now. But for the moment our job is to divine what the British people want. I believe there is broad agreement on what this is. I am therefore inviting Labour’s leadership to meet me to see how we can take this forward on a bipartisan basis. It must be the right thing to do. Even if it ultimately costs me my job.”

• Simon Jenkins is a Guardian columnist