Theresa May has rejected alternatives to her Brexit deal, urging MPs to think about the consequences for their constituents of voting it down.
The PM, who is in Argentina for a G20 summit, ruled out moving to Norway-style deal with the EU, an idea being promoted by some Tory MPs.
She said this was unacceptable as it would see freedom of movement continue.
Labour argues a better deal could still be done but the PM has said they have not put forward a proper alternative.
By threatening to oppose her deal in a Commons vote on 11 December, Mrs May said Labour were effectively advocating leaving without a deal.
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The Labour leadership has said it is ready to support a cross-party amendment to the vote that would rule out no-deal.
The amendment would not be binding but it would be hard for the PM to ignore it, if it is passed by Parliament.
Leading Tory Brexiteer Jacob Rees-Mogg has, meanwhile, warned against efforts to “frighten” people into backing what he called “a non-Brexit Brexit”, in the Daily Telegraph.
It is widely expected that MPs will reject it the EU withdrawal agreement and blueprint for a future trade deal agreed with the EU on 11 December.
But speaking to reporters on her flight to Buenos Aires, Mrs May insisted she had not given up hope of winning the vote.
If MPs failed to back her it would mean “division and uncertainty” for Britain, she warned.
“Let’s focus on the deal that we have negotiated with the EU, a deal which is good for the UK and good for their constituents,” she said.
Mrs May said people she had met outside Westminster in the last few days had given her an “overwhelming” sense that they wanted MPs to back her deal.
Analysis: No clues over possible ‘Plan B’
By Laura Kuenssberg, BBC political editor
However many ways the question was put to Theresa May during a 20-minute press huddle on board the government’s Voyager plane, she was resolutely and determinedly not going to let much slip.
What will she do if she can’t get her vote through? Is there a plan B? Could there be a Norway-style relationship with the EU? Could there be another referendum?
Westminster’s awash with speculation and gossip about what might happen next if her Brexit compromise is killed off by her colleagues.
What is happening with Brexit right now?
Mrs May is due to join US President Donald Trump, China’s President Xi Jinping and Japan’s Shinzo Abe as well as European Council President Donald Tusk and European Commission chief Jean-Claude Juncker at the two-day summit of the G20 group of leading economies.
She is expected to tell world leaders her Brexit deal negotiated with the EU will be good for the global economy.
Mrs May will highlight her plans to strike a free trade agreement with the EU.
But she will add: “For the first time in more than four decades, the UK will have an independent trade policy.
“We will play a full and active role on trade on the global stage, working with friends new and old, at a time of unprecedented global inter-connectedness.”
The summit comes after President Trump suggested that the negotiated deal could threaten any future US-UK trade deal.
Ministers step up efforts to sell deal
International Trade Secretary Liam Fox is to defend Mrs May’s deal, saying that while it will not please everyone, critics “are yet to face up to” the “tough choices” she had to make.
In a speech at the Portbury Royal Docks, near Bristol, Mr Fox, who campaigned for Brexit, will also play down reports suggesting that UK economic growth after Brexit would be slower than if the UK stayed in the EU.
He told the BBC there were alternatives to Mrs May’s deal which would give the UK a freer hand to strike other trade deals but that could come with a “price” in terms of reduced access to EU markets.
“The European market is 44% of Britain’s exports,” he told Radio 4’s Today. “That is a lot of jobs, a lot of profits. The government is not there to do what we want, we are there to do what is in the national interest.”
The Financial Times says Mrs May is enlisting the support of senior Brexiteers such as Michael Gove and Geoffrey Cox to try and sell her controversial Irish “backstop” plan to sceptical Tory MPs.
Mr Fox said he was not “enthusiastic” about the backstop, which could see the UK enter a customs partnership with the EU until its future relationship is sorted out and without the unilateral right to pull out.
But he insisted the chance of the backstop, described as an “insurance policy” by Mrs May, actually coming into force was slight as it was just as “unpalatable” to other EU members, including the Republic of Ireland.
Brexit: May rejects all alternatives to her EU exit deal}