Ben Wallace could quit the cabinet if Liz Truss dumps a key defence spending pledge, HuffPost UK understands.
The defence secretary wants the prime minister to stick to her promise to increase the armed forces budget by 2.5% of gross domestic product by 2026.
However, Jeremy Hunt - who took over as chancellor from Kwasi Kwarteng last week - has said all departments will have to prepare for spending cuts as the government tries to repair the damage done by the mini-Budget.
Wallace has told friends that Truss will continue to have his support so long as she sticks to the 2.5% pledge.
Asked whether that commitment remained in place, the prime minister’s official spokesperson today refused to do so.
Instead, he would only commit to a separate promise to spend 3% of GDP on defence by 2030.
He said: “You’ve heard from the chancellor on this.
“We are obviously committed to maintaining the UK’s position at the forefront of NATO, that’s why the PM committed to raise defence spending to 3% of GDP by 2030.
“The shape of that increase will be set out at future spending reviews in the normal way.”
Hinting that the 2.5% pledge will be dropped, he added: “The structure of how we get to that 3% increase over a number of years will be determined between the MoD and the Treasury.”
Armed forces minister James Heappey today said he would resign if the 3% commitment is dropped.
He told Sky News: “The commitment the prime minister made is 3% by 2030 and to be clear, like [Ben Wallace] that’s something that I believe must be delivered given the need to keep our nation safe given increasingly uncertain times.
“If in the very immediate term there is a requirement to look at what we can do to help the Treasury out, that’s a discussion for the chancellor to have with the secretary of state.
“But I am confident that the prime minister and the chancellor, and the foreign secretary, and frankly everyone else around government, understands the importance of investing in our nation’s armed forces and our defences at a time when the UK interest at home and abroad is under such threat.”
Wallace - who has been touted as a possible prime minister if Truss is forced from office - told The Times: “I want to be the secretary of state for defence until I finish. I love the job I do and we have more to do.
“I want the prime minister to be the prime minister and I want to do this job.
“I say to the colleagues who think our role is to feed the instability within the party, by proposing other people as leaders no matter who they are, (you) are doing a disservice.”