Rishi Sunak has hinted he would not take a cabinet post if Liz Truss wins the Tory leadership race, saying ministers "need to agree on the big things".
"I am not focused on all of that and I doubt Liz is," he told BBC Radio 2.
"I am not thinking about jobs for me or anyone else."
He appeared to allude to the potential for cabinet clashes, adding: "One thing I have reflected on a bit being in government and cabinet [is] you really need to agree on the big things because it's tough, I found, if you don't.
"I wouldn't want to get into a situation like that again."
Mr Sunak, the underdog in the leadership race, also admitted that some Tory party members are still angry at him for quitting Mr Johnson's government.
But he insisted he was not paying attention to polls suggesting he is set to be defeated by Ms Truss.
"If I actually spent all my time looking at the polls or reading newspapers, I probably wouldn't get out of bed in the morning to do all these things," he said.
He also rejected suggestions that his campaign has not been "politically savvy" as he said he just wants to be "honest" with voters about the state of the British economy.
Truss 'promising the earth to everybody'
He said: "I'd love a tax cut, who doesn't? Liz's plans are promising the earth to everybody, I don't think you can have your cake and eat it."
The Tory leadership rivals have clashed repeatedly over how to tackle the cost of living crisis, in what has become an increasingly heated contest.
Mr Sunak's campaign team have attacked Ms Truss for focusing on tax cuts rather than direct support payments to help with rising energy bills.
Earlier on Sky News, Tory MP Kevin Hollinrake, who backs Mr Sunak in the leadership race, claimed that the foreign secretary's cost of living plans could put people on the streets.
Ms Truss has argued that tax cuts will help to grow the UK's economy and boost prosperity.
Her team have not ruled out providing further help to people this winter, but say they will not reveal what she will do until the leadership contest is over, on 5 September.
Having an emergency budget next month - in which Ms Truss plans to make long-term funding pledges if she becomes prime minister - has been a key part of the frontrunner's campaign to get into Number 10.
But going ahead without an OBR forecast has been branded "worrying" by an economist and expert in government finance, while the team behind Mr Sunak accused her of wanting "to avoid independent scrutiny".
The OBR provides forecasts for all budgets as part of the founding law of the body, enacted in 2010, and despite being funded by the Treasury, it is fully independent.
But a source in the Truss campaign told Sky News that a forecast wasn't necessary for a "targeted fiscal event".
A Truss campaign spokesman said: "The cost-of-living crisis means immediate action is required.
"A Truss government would seek to act as soon as possible to help people across the UK, by cutting taxes and introducing a temporary moratorium on energy levies."