Conservative hard Brexiteers have released proposals which they believe could allow the UK to leave the EU's single market and customs union without the need for a hard border in Ireland.
The European Research Group of Tory backbenchers - led by Jacob Rees-Mogg - believe the British government has allowed the border question to become a roadblock to achieving a Canada-style Free Trade Agreement with the EU.
In a new paper, they propose the government should agree equivalence of UK and EU regulations and conformity assessment for all agricultural goods on the island of Ireland.
Northern Ireland and the Republic would be maintained as a Common Biosecurity Zone after Brexit, allowing the smooth movement of these products across the border.
"Since UK and EU standards are identical and will remain identical at the point of departure, determining equivalence after Brexit should be straightforward," said the document.
For other goods, the ERG said existing simplified customs procedures could continue to be used to avoid the need for checks at the border.
Larger companies would use "trusted trader" schemes to clear their goods for export and import, and other declarations would be incorporated into the existing system used for VAT returns.
"The EU will be able to maintain the integrity of its internal market without erecting a hard border along its border with Northern Ireland," said the ERG paper, launched in Westminster.
"At the same time, the United Kingdom will be able to develop a fully independent trade policy rather than remaining a rule-taker.
"The one element of 'alignment' necessary is the maintenance of the current Common Biosecurity Zone covering the island of Ireland, and this is not contentious.
"The necessary procedures described can all be implemented within the existing legal and operational frameworks of the EU and the UK, based on the mutual trust on which regular trade depends.
"Rational, pragmatic approaches can ensure that the vital trade across the border is maintained. At the same time, this allows the United Kingdom to conduct an independent trade policy without threatening the integrity of the EU single market."
The ERG said its proposals could be delivered without the need for any new infrastructure at the border and without weakening north-south co-operation.
"There is nothing which would reduce our commitment to the Belfast Agreement, or which might jeopardise peace in Northern Ireland," the group said.
"Harnessing the latest developments in international best practice can deliver continued co-operation and prosperity in the best interests of the United Kingdom and the Republic of Ireland."
Mr Rees-Mogg said he wants Theresa May to remain in place but to ditch her Chequers plan.
He said the "policy needs to be changed" but he was "supporting" the prime minister.
Mr Rees-Mogg said Mrs May was "fantastically dutiful".
He said: "I have long said, and repeated again and again, that the policy needs to be changed but I am supporting the person.
"Theresa May has enormous virtues, she is a fantastically dutiful Prime Minister and she has my support.
"I just want her to change one item of policy."
Former Brexit minister David Davis said he thinks "we have got a very good" prime minister, but said disagrees with her on "one issue".
"She should stay in place because we need stability and we need decent government as the backdrop to what we are doing in the coming six months."
