The next British prime minister should strive to reach a Brexit deal, Theresa May has said as the race to succeed her entered its final stretch.
Boris Johnson and Jeremy Hunt will take part in the final hustings of the campaign tonight.
Offering advice to her successor, Mrs May said they should find a way to leave the European Union that was “in the national interest”.
Former foreign secretary Mr Johnson, the favourite to become the next British prime minister, has made a “do or die” pledge to leave the EU on October 31 with or without a deal.
Current Foreign Secretary Mr Hunt has said he could delay Brexit beyond that point if a deal was in reach, but has not ruled out walking away from negotiations without an agreement.
Answering questions after her final major speech as British Prime Minister, Mrs May said the “best route” for Brexit was to leave with a deal.
“I think we had a good deal, but Parliament wasn’t willing to come behind that with a majority.
“It will be for whoever succeeds me to find a way through that and I believe that the aim must still be to leave – ie to deliver on the vote of the referendum – but to do so in a way that is in the national interest.”
She defended the Irish backstop, one of the most contentious parts of her Brexit deal.
Both contenders in the race to succeed her have declared that the backstop – a contingency plan to ensure there is no hard border with Ireland – is dead and should be replaced.
But explaining why it was necessary, Mrs May said: “At the heart of the Belfast Good Friday Agreement is an essential compromise that people who are Irish can live in Northern Ireland as part of the UK but on a day-to-day basis, in their business and their own personal activities, operate without any encumbrance on their operation across that border.
“I believe it’s important that we are able to sustain that into the future.”
Meanwhile Chancellor Philip Hammond launched an attack on one of Mr Johnson’s most prominent supporters, claiming it was “terrifying” that anyone close to the potential next administration could support a no-deal Brexit.
European Research Group chairman Jacob Rees-Mogg used a Daily Telegraph opinion piece to dismiss the “silliness” of Treasury forecasts suggesting a £90 billion hit to the economy.
Mr Hammond said: “Happy to debate scale of negative impact of no deal on the economy – but terrifying that someone this close to a potential future government can think we’d actually be better off by adding barriers to access to our largest market.”
Brexit Secretary Stephen Barclay also laughed off the £90 billion figure, insisting that it was a forecast for 2035 and did not factor in any mitigation measures a government might introduce.
He suggested a no-deal Brexit was more likely than people had claimed, saying it was “underpriced”.
Mr Barclay backs Mr Johnson, who has claimed the chances of a no-deal Brexit were a “million to one against”.
Cabinet colleague Amber Rudd, who backs Mr Hunt, insisted whoever won the leadership contest would have to compromise on EU withdrawal.
The Work and Pensions Secretary said she was “surprised” by the hardline stance taken by the Foreign Secretary and Mr Johnson on EU withdrawal in Monday’s leadership debate.
Ms Rudd told the Politico website: “I think they will find they have to compromise.
“I was surprised by what they both said and I think their views will collide with the reality when whichever one wins, starts negotiating and starts dealing with a Parliament which may be more difficult than they think to engage with.”