A senior Tory Brexiteer has attacked Theresa May’s decision to put her de facto deputy on the government’s team for the crucial final stretch of negotiations with the EU.

In a sign of the fragility of the Tory truce over Brexit, Dominic Raab suggested David Lidington’s presence on the negotiating team may leave Britain with an “unpalatable” deal.

Raab attacked his former cabinet colleague as a Remainer “widely seen” as a supporter of a customs union compromise which would amount to a “direct and flagrant breach” of the Conservatives’ 2017 election manifesto.

The direct attack on one of May’s closest allies will serve as a warning from the Brexiteer wing of the Tory Party that she should not compromise too far in talks with the EU.

It comes after the PM brought warring Tories together to try and seek “alternative arrangements” to the controversial Irish border backstop.

But her choice of Lidington alongside Attorney General Geoffrey Cox and Brexit Secretary Steve Barclay to shake up her negotiating team has proven controversial among Leavers.

In an interview with the House magazine, ex-Brexit Secretary Raab said: “I think the problem is that if David Lidington is leading it – and he’s one of the most brilliant ministers that we’ve got and he’s got huge diplomatic expertise – I sense there’ll be a perception, perhaps unfairly, that this is a guy who wanted us to stay in the EU.”

Raab, who quit his post to vote against May’s draft Brexit deal, said Leave supporters would be sceptical of Lidington’s ability “to get this deal delivered in a way that is palatable back home”.

“I’m hopeful that we’ll get some compromise from the EU, but it’s probably 50/50. The problem is that if we get some substantive compromise which has to be weighed up, the risk is if you don’t have a Brexiteer leading that process, that actually we haven’t fought hard enough for it. Whether that’s fair or not, that’s probably the perception,” he added.

“There may be also a perception that they don’t have to give so much in Brussels to someone who was on the Remain campaign side and is widely seen as an advocate of the customs union option.”