Rachel Reeves has given her support to Andy Burnham to be the next prime minister, despite reports that she is likely to be moved out of the role of chancellor if he becomes the next Labour leader.

The chancellor told the BBC she and Burnham were friends and did not appear to rule out accepting a more junior cabinet position. “I’m supporting Andy to be prime minister,” she said.

Asked about reports that Burnham could offer her a more junior role in his cabinet, Reeves said: “I’m not going to pre-empt the decisions that the new prime minister will make. I’m backing Andy. I think he’d be a great prime minister, but those are his decisions, not mine to make.”

Reeves, who became the first female chancellor after Labour’s landslide election victory in 2024, attended Burnham’s Westminster Hall rally on Monday and was not present as outgoing prime minister Keir Starmer gave his resignation speech.

However, she told the broadcaster ahead of a planned address at the British Chamber of Commerce’s global annual conference on Thursday that “no one could doubt” her commitment to Starmer, with whom she has worked side by side since he became prime minister.

“I’ve been by his side for six years now as shadow chancellor and then as chancellor of the exchequer,” she said. “I know that whoever is prime minister and chancellor in the future will inherit a stronger economy than the one I inherited two years ago.”

Her support comes after reports that one of Reeves’s top aides has urged some of the UK’s biggest companies and trade associations to lobby Burnham to keep her in the top job at the treasury.

According to Sky News, officials including Katie Martin, who was appointed as Reeves’s business adviser in January, is said to have called a number of major companies in the insurance, banking, defence and other sectors earlier this week to make the case for “stability” and “continuity”.

Speculation about Burnham’s choice as chancellor has grown as the new Makerfield MP’s route to 10 Downing Street has become clearer. The next resident of No 11 could define his time in office, with MPs saying it will give the clearest sign yet of how radical he intends to be.

Burnham’s supporters are said to be divided over the choice, with a briefing war breaking out between advocates of the former health secretary Wes Streeting and those close to the energy secretary, Ed Miliband.

Some allies see Streeting as the more reassuring choice for the business community and fossil fuel industry, but others have lobbied for Miliband, whom they see as more likely to back radical policy ideas and push through reforms.

Some within Labour have cautioned against appointing Miliband, with the chief secretary to the prime minister, Darren Jones, appearing to suggest the former party leader would not meet his “tests” for a new chancellor.

Jones said any new chancellor should not seek to “control” the prime minister, and would have to “reassure” markets, trade unions, MPs and the public.

Burnham moved a step closer to taking the helm of the Labour party on Wednesday after Jones said he would not stand in a Labour leadership contest.

Former armed forces minister Al Carns, who resigned earlier this month over defence spending, is yet to rule himself out of any potential race. On social media on Wednesday evening, Carns said the country “needs a proper debate about where we go next. Not a reshuffle. Not a few degrees of course correction. The big, difficult, honest choices we’ve spent 30 years avoiding.”

The former marine set out “five tests” which he said anyone leading the country should have to meet, including more defence spending and implicit criticism of the government’s energy policy.