Labour will be bolder and quicker to act under Andy Burnham, a Cabinet ally of the prime minister-in-waiting said.
Culture Secretary Lisa Nandy said the party would “wear our hearts on our sleeve” more than under Sir Keir Starmer’s leadership.
Mr Burnham requires just one more MP to nominate him to make it mathematically impossible for anyone to stand against him and Home Office minister Mike Tapp said he would back him when the Commons returns on Monday.
When MPs left Westminster on Thursday, Mr Burnham had the backing of 322 of the 403 Labour MPs.
The total means that there are still 81 Labour MPs left who could nominate another contender, the minimum needed to get on to the ballot, but Sir Keir and some other party office holders are unlikely to nominate anyone.
Even before nominations opened, Mr Burnham seemed almost certain to enjoy a coronation as the only declared candidate in the race to succeed Sir Keir, with him likely to take the party leadership at a special conference in a week’s time and then become prime minister on July 20.
The Culture Secretary told BBC Radio 4’s Today: “I think there will be two things that will be different under Andy Burnham.
“The first is that it will be faster and bolder and he’s willing to think very differently about how we deliver that change.
“No 10 for the North has attracted a lot of interest, but that really is about shifting the centre of gravity in the country, so that all parts of the country are seen and heard and are able to contribute.
“But the second thing that I think will be different is that I think we will wear our hearts on our sleeve more. I think people will see us taking the fight to any system that stands in the way of them living better lives.
“And I really think, at the moment, at a time when trust in the power of government to change people’s lives is very weak, that that is an enormously important thing.”
Mr Burnham said he was “deeply grateful” to the 322 MPs who had backed him, saying their support “comes from across the PLP (Parliamentary Labour Party) and reflects a shared belief that Britain needs a new approach to politics”.
He added: “I want to empower MPs to bring the experiences of their constituents into the heart of government and harness the full breadth of our Labour movement, drawing on all its traditions and beliefs in pursuit of a common purpose.
“I want to thank every colleague who has nominated me for their commitment to that vision.”
Almost every member of the Cabinet backed Mr Burnham, as did former health secretary Wes Streeting and former armed forces minister Al Carns, who had previously been regarded as potential challengers.
Key Starmer ally Steve Reed was one of only three Cabinet members who did not nominate Mr Burnham on Thursday.
Home Secretary Shabana Mahmood is chairwoman of Labour’s ruling national executive committee and Anna Turley is Labour chairwoman, so are likely to be sitting out the process because of their party roles.
As nominations opened on Thursday, Sir Keir told reporters he thought Mr Burnham would make a good prime minister, saying they had known each other “a long time”.
Asked whether Mr Burnham would be a better prime minister than him, Sir Keir replied laughing: “These are things best judged by other people.”
One issue that Sir Keir has left for Mr Burnham to deal with is finding billions of pounds to fund defence.
There is a £4.7 billion gap over four years in the defence investment plan and billions more will be required to meet Nato commitments to spend 3.5% of gross domestic product on the military by 2035.
Ms Nandy suggested that Andy Burnham might look at “other options” to fund defence rather than move money from within existing government spending.
Her comments leave open the prospect of Mr Burnham hiking taxes or increasing borrowing to provide the money needed to meet the UK’s Nato commitments.
“What I’m absolutely convinced about, having known him well now for 17 years, is that whether we fund defence is not going to be a question,” she said.
“The question will be how.”
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