Theresa May has ruled out any plan B involving a Norway-style compromise deal with the Labour party in order to deliver a parliamentary consensus on Brexit, saying the opposition party’s refusal to accept the backstop arrangement put the UK on a course for no deal.

Influential backbenchers, including former Tory minister Nick Boles and Labour’s Stephen Kinnock, have been developing a compromise proposal based on membership of the European Economic Area plus a negotiated customs union, believing it is the only version of Brexit that could attract enough Labour and Tory votes to deliver a parliamentary majority.

Some cabinet ministers are understood to be attracted to the plans as an alternative if May’s negotiated deal fails to pass the House of Commons.

However, on Thursday May repeated her rejection of the “Norway plus” model and suggested she would not be prepared to offer it as a compromise arrangement because it would mean the continuation of freedom of movement. That is regarded in Downing Street as the hardest of the prime minister’s red lines.

Speaking to reporters en route to the G20 summit in Argentina, the prime minister remained defiant that her version of a Brexit deal could win the vote in less than a fortnight’s time. More than 90 Conservatives and the overwhelming majority of the Labour MPs have publicly confirmed they will not back it.

“I’ve been very clear about my position, we won’t be in the customs union,” she said, onboard her RAF Voyager plane to the two-day summit in Buenos Aires.

“What you see in the political declaration is what would be a deal for the United Kingdom that is not Norway, it is not Canada, it is a more ambitious free trade agreement than Canada, and it ends free movement – which Norway doesn’t do.”

Asked whether the model would be the only way to win Labour votes, the prime minister suggested the end result of the strategy put forward by shadow Brexit secretary Keir Starmer would be the UK leaving with no deal.

“You talk about if a Norway-style strategy would bring Labour along with it – if you look at the Labour party amendment that they’ve put down to the motion on the 11th of December, actually what they are doing is advocating rejecting the deal we’ve negotiated with the European Union without having any proper alternative to it,” she said.

“They say they don’t want no deal, but by appearing to reject a temporary backstop, they are effectively advocating no deal. Without a backstop, there is no deal.”

May suggested she believed there was no compromise that could involve Labour. “What they actually want to see is another general election,” she said. “And that means they are not acting in the national interest, they are putting their narrow party interest first.”

A divided country is not a country that prospers Theresa May

The prime minister insisted the result of a vote was not a foregone conclusion despite her mutinous backbenchers’ stated intentions. “Everyone said we would not get a deal, and now we’re in the position of having a deal, all you seem to want to be asking about is the next stage,” she told reporters. “We haven’t had the vote yet. Let’s focus.”

Quick Guide What is the common market 2.0/Norway-plus Brexit option? Show This soft Brexit compromise has been championed as a plan B for leaving the European Union. It is based on Norway’s relationship with the EU, which is outside the bloc and the customs union but inside the single market. Under the plan the UK would have to join Norway, Liechtenstein and Iceland in the European Free Trade Association (Efta), which would then allow it to participate in the European Economic Area (EEA). The ‘plus’ in this option refers to a temporary customs union with the EU, which would need to be negotiated to avoid a hard border on the island of Ireland. This arrangement would remain in place until the EU and UK agreed a specific trade deal. The option has the advantage of being as close to the EU as possible without full membership, and it would do away with the need for the problematic backstop for Northern Ireland. Like Norway, the UK would be outside the common fisheries and agriculture policies, and would not be subject to the European court of justice. But it crosses a key red line for Brexiters by continuing freedom of movement, one of the preconditions of single market membership. It would also limit the UK's ability to negotiate its own trade deals while a new customs arrangement is under discussion. And it would require continued financial contributions to the EU without an influence, as the UK would no longer have MEPs or a seat on the European Council. It also isn't entirely clear that the UK would be welcomed into Efta.

May suggested those MPs who had sworn to vote down her deal were going against the interests of their constituents. “I ask every member of parliament to think about delivering on the Brexit vote and doing it in a way that is in the interests of their constituents – because it protects the jobs and livelihoods of their constituents.

“If the vote is not supported then we will see more division and more uncertainty. A divided country is not a country that prospers.”

Speaking at the liaison committee of MPs before she set off for Buenos Aires, May was pressed on whether she had a plan B for avoiding a no-deal scenario and the dire economic consequences the Bank of England has predicted.

May suggested the result of rejection would be a ramping up of preparations for no deal. She later told reporters that loss of the government in parliament would set in motion “practical preparations that they would need to make for a no deal” to mitigate the worst-case scenario.

“The point of the preparations ... is to ensure that we can take action to mitigate the impact of no deal,” she said. “We are doing what every sensible government would do.”

Speaking about the upcoming TV debate, May said she would debate only Jeremy Corbyn and not any hard Brexiter such as Boris Johnson, or any campaigner for a second referendum.

She said the country had moved on from the leave-versus-remain argument and the debate was “looking ahead to the vote”. She said it would be a chance to present her deal to the British people and draw comparisons with Labour’s position.