(Bloomberg) -- Philip Hammond warned Prime Minister Boris Johnson he’ll work through Parliament along with other former Cabinet ministers to try to stop the U.K. leaving the European Union without a divorce deal.

Johnson has said he’s committed to delivering Brexit “do or die” on Oct. 31. While he says he wants to do so with a deal, he is yet to meet any EU leaders as the clock ticks down. Instead, he’s insisting that they must reopen the deal negotiated by his predecessor, Theresa May, and remove a section designed to prevent a hard border between the U.K. and Ireland.

To persuade the bloc to do that, Johnson’s government has ramped up its rhetoric about preparations for a no-deal Brexit. But that has provoked those in his own Conservative Party who argue this would do huge economic damage.

“Leaving the EU without a deal would be just as much of a betrayal of the referendum result as not leaving at all,” Hammond, who was May’s Chancellor of the Exchequer, told the BBC on Wednesday. “To set the bar for negotiations so high that we inevitably leave without a deal would be a betrayal. The prime minister said he would get a deal and we want to see him deliver that deal.”

Hammond said he was “very confident” Parliament had the means to stop Johnson, but said that didn’t mean there was a majority to do so. His argument was backed up by a letter to Johnson signed by Hammond and 20 other Tories -- including several former Cabinet ministers -- urging him to change course.

“We are alarmed by the ‘Red Lines’ you have drawn which, on the face of it appear to eliminate the chance of reaching agreement with the EU,” they wrote in the letter, The Sun newspaper reported.

Even with his Northern Irish Democratic Unionist Party allies, Johnson has a working majority in Parliament of just one. That means Hammond and his group have the numbers, at least in theory, to compel a shift in strategy.

In a separate warning, Speaker of the House of Commons John Bercow said on Tuesday he would fight any attempt by the government to suspend Parliament to force through a split many lawmakers oppose. His support to MPs trying to stop a no-deal Brexit has already proved crucial, with parliamentary rules changed to allow different maneuvers.

To contact the reporter on this story: Robert Hutton in London at rhutton1@bloomberg.net

To contact the editors responsible for this story: Tim Ross at tross54@bloomberg.net, Stuart Biggs, Mark Williams

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