Tory MP George Freeman has revealed he has changed his mind and will now vote in favour of Theresa May’s Brexit deal.
The Mid Norfolk MP, who used to chair the prime minister’s policy board, said he would back May “with a heavy heart”.
It is widely expected that the Commons will vote down the PM’s plan on Tuesday.
Cabinet ministers have stepped up warnings about the UK defaulting to a no-deal Brexit if parliament cannot agree an alternative.
Environment secretary Michael Gove told MPs no-deal would see “economic turbulence” and Business Secretary Greg Clark said it would be a “disaster”.
Speaking in the Commons on Thursday, Freeman said it would be “woeful” for the government to oversea a no-deal exit.
“Don’t accuse me please of Project Fear – this is serious Project Business that we serve,” he said.
“I will, with a heavy heart, on Tuesday vote for this deal because we’re now in the dying stages and no deal is unconscionable.
“But I beg colleagues to ask their front benches in pursuit of something we can all be proud of.”
Freeman said if May’s deal was in the end defeated, he would push for a soft Brexit on the EFTA or Norway model.
In December, Freeman told HuffPost UK he expected a general election will be triggered in the next 12 months, as Brexit will end May’s premiership.