Andrea Leadsom has said Theresa May is the right person to be prime minister – “at the moment”.

The Commons leader and self-described “arch-Brexiteer” said she had decided not to resign from Cabinet in order to make “absolutely sure” Britain does not end up in the backstop.

“All the way through I’ve had conflicting thoughts and I’ve had to consider whether I can live with things,” she told BBC Radio 4′s Today programme on Wednesday morning.

“But at the end of the day this deal is the best combination that we’re going to get and so I just urge colleagues to look at it carefully to give it a real chance.”

May yesterday suffered a string of damaging Commons defeats, including being forced to give MPs a say on what happens if her Brexit deal is voted down next Tuesday.

Ministers also had to agree to publish the “final and full” legal advice to Cabinet on the withdrawal agreement as the government was found to be in contempt of parliament for not already doing so.

The advice is due to be published at 11.30am today.

Asked if May was the right person to lead the party and the country, Leadsom said she “certainly is at the moment”.

Pressed on the question, she added: “I have never and will not start predicting the future.”

The prime minister was dealt a further blow last night when Mark Harper, a former Tory chief whip, predicted the government would lose Brexit vote by more than 80 votes.

Harper, who has never rebelled against his party before, told The Daily Telegraph May’s deal was “not acceptable” because it threatens “the integrity of our country”.

Education Secretary Damian Hinds told BBC Newsnight the “difficulties” endured by the government would help “focus minds” of Tory MPs.

“There is one deal on the table. If that were not to be passed, then I think we go into a period of some uncertainty about what would happen instead,” he said.