The highly ambitious Manchester Mayor will appear alongside transport union baron Mick Lynch at a cost-of-living rally called “Enough is enough” tonight. Mr Burnham also appeared to publicly criticise the Labour leader’s reluctancy to back the renationalisation of the energy industry.
His comments are likely to be seen as a challenge to Sir Keir’s authority.
The party boss has urged Labour politicians against being seen arm-in-arm with those on strike.
Sir Keir has said “the Labour Party in opposition needs to be the Labour Party in power”, arguing Government ministers cannot join picket lines.
But the Manchester mayor this morning said he would be proud to also join Mr Lynch on a picket line and there should be no issue with Labour politicians showing their support.
Next Labour leader: Andy Burnham tops polls to take on Starmer
He defied calls from some in his party to go further and commit to nationalising the industry, saying: “If you go down the nationalisation route, then money has to be spent on compensating shareholders.
“And I think in an emergency like this, a national emergency where people are struggling to pay their bills, I think the right choice is for every single penny to go to reducing those bills.”
Mr Burnham has been accused of positioning himself for a future Labour leadership bid for months.
He has openly admitted he would still like to take on the top job.
However, this morning he denied he was looking to oust Sir Keir and said the Labour leader had his “full support”.
Refusing to rule out standing for leader, he said: “Perhaps one day, if that would be something people would support.
“But, not now, because we’ve got a leader of the Labour Party who is providing leadership during the cost-of-living crisis and I’m happy to give my full support to Keir.
“And I’ve got a job to do in Greater Manchester.”