Boris Johnson has urged Conservative lawmakers to support his plan to override part of the Brexit withdrawal agreement.
In a zoom in with about 250 of them, he said the party should not return to “miserable melee” in Europe.
The EU has warned the UK that it could face legal action if it does not eat the controversial elements of the domestic market bill by the end of the month.
And the Tory MP has proposed amendments to the bill, which would affect trade between Britain and Northern Ireland.
Meanwhile, the European Parliament has threatened to scrap any UK-EU trade deal if the bill becomes UK law.
Mr Johnson has less than five weeks to agree on a deal before the October 15 deadline – after which he says he is ready to “walk away”.
Informal talks are set to resume on Monday, with the next official round of talks – March 9 – starting in Brussels on September 28.
The Internal Market Bill, which will be formally debated in the House of Commons for the first time on Monday, addresses the Protocol of Northern Ireland – part of a Brexit withdrawal agreement designed to prevent the return of the strict border to the island of Ireland.
If enacted, it would give UK ministers the power to amend or “disappear” rules relating to the movement of goods between Britain and Northern Ireland, effective January 1, if the UK and EU fail to enter into a trade deal.
The EU says planned changes should be scrapped or they risk endangering UK-EU trade.
But the government has rejected the demand, arguing the need for action in the bill to safeguard the UK’s integrity and the peace process in Northern Ireland.
The prime minister did not raise questions in his zoom call with lawmakers on Friday and the weak signal meant video and audio dio connections were lost for several minutes.
He called for “overwhelming support” for the bill, describing it as “absolutely important” to prevent a foreign or international organization from having the power to break into our country.
Mr Johnson added that they would not “threaten the border below the Irish Sea”.
But he said the UK and the EU still had a very good chance of reaching a deal in mid-October, similar to the one previously agreed between the Central European Union and Canada – which got rid of tariffs on goods.
The BBC’s chief political correspondent Vicky Young said Tory MPs were “looking for a sign of a compromise” because Mr Johnson “could not believe the government was ready to break international law”, but the prime minister “opened his mouth”.
‘Serious misunderstanding’
In a column in the Daily Telegraph, Mr Johnson defended the government’s plans to override parts of the withdrawal agreement.
He accused the EU of adopting an “extreme” interpretation of the Northern Ireland Protocol to impose a “full-fledged trade border under the Irish Sea” that could halt the flow of food from Britain to Northern Ireland.
“I have to say that we have never seriously considered being ready to use the EU treaty, to negotiate in good faith, to blockade a part of the UK, to cut it off,” he said.
The PM said it was clear there could be “serious misunderstandings” between the UK and the EU over the withdrawal agreement.
He said the UK must avoid the so-called “disaster” of the EU in order to “destroy our country” and “threaten peace and stability in Northern Ireland”.
‘Harmful Act’
Conservative backbencher Sir Bob Neal, chairman of the Commons Justice Committee, said he was not reassured by the prime minister’s zoom call.
He is preparing to amend the bill in an attempt to force a separate parliamentary vote on any change to the withdrawal agreement.
“I believe this is a potentially damaging act for the country, it will damage our reputation and I think it will be difficult to strike a trade deal going forward,” he said.
At the same time as the Prime Minister was speaking, the European Parliament declared that “any trade deal between the UK and the EU will not be recognized under any circumstances” if the UK authorities withdraw or threaten to breach the agreement.
Northern Ireland Secretary Brandon Lewis has accepted some parts of the bill, which is contrary to the treaty signed by the UK and the EU, “would break international law in a very specific and limited way”.
The Conservative Party is uneasy about the matter, with former leaders Theresa May, Lord Howard and Sir John Major urging Mr Johnson to reconsider.