Andy Burnham is almost guaranteed to be the next British prime minister after 322 Labour MPs nominated him to take over from incumbent Keir Starmer.

The numbers mean there are only 81 British Labour MPs left who could nominate another contender, the minimum needed to get on to the ballot.

But convention dictates that the outgoing leader does not nominate a candidate, meaning in reality there are no longer enough undeclared MPs to back an alternative to Burnham.

Andy Burnham is expected to jog into the role of prime minister on July 20. Photo: AAP 

The former Greater Manchester mayor secured the nominations – amounting to 80 per cent of the parliamentary party – by 5pm on Thursday (local time). Under the party’s rules, it was the first day MPs could formally back a leadership candidate.

Even before nominations opened, Burnham seemed almost certain to enjoy a coronation as Labour leader as the only declared candidate in the race to succeed Starmer.

But the size of his support in the parliamentary party means even a late challenger has virtually no hope of securing the required nominations.

Starmer said on Thursday, as nominations formally opened, that Burnham would make a good PM.

“I have known him a long time, I’ve worked with him when I first came to parliament, in his team directly,” he said.

Asked whether Burnham would be a better prime minister than him, Starmer replied laughing: “These are things best judged by other people.”

In an interview with The Guardian on Thursday, Burnham ‌criticised Starmer’s initial reaction to Israel’s military campaign in the Gaza Strip in October 2023, which came after an attack on Israel by Hamas-led gunmen.

“We’ve got to do more to ‌put pressure ‌on the ⁠Israeli government … Yes, we have taken some important ​steps … But let’s be honest, the UK was too slow to call for a ceasefire. And we must now do more to strengthen our approach,” he said.

Starmer initially resisted calls from within Labour, including from Burnham ⁠who was a regional mayor at ‌the ​time, to demand a ceasefire, instead backing a humanitarian pause in the fighting.

Nominations for the Labour leadership remain open until July 16. But Burnham’s last possible rival, Birmingham MP Al Carns, ruled himself out of the running on Wednesday, leaving a clear path.

In the absence of any other candidates, Burnham will be formally declared Labour leader at a special conference on July 17. He is expected to then become prime minister on July 20.