Backers of Andy Burnham are set to take on Labour's ruling body to make sure he can stand in any leadership election – at the expense of Angela Rayner.

If, as expected, Health Secretary Wes Streeting moves to challenge Keir Starmer on Thursday, the Mayor of Greater Manchester will have to break his current silence and throw his hat into the ring or see his opportunity vanish.

His supporters in the Tribune group, lead by former Transport Secretary Louise Haigh, are ready to launch a campaign to ensure the party's ruling executive committee do not block him from standing in a by–election for a second time.

They are set to fight for his inclusion in any leadership race, leaving former deputy PM Ms Rayner out in the cold.

On Wednesday, questions swirled in Westminster over whether the self–styled 'King of the North' would finally clarify what constituency he has set–up to spark the by–election.

He needs to get back into Parliament in order to make a move to become Prime Minister.

MPs were demanding answers, with one warning 'there's lots of scepticism' about the emphatic assurances from Mr Burnham's supporters.

Despite repeated denials, the name of Rusholme MP Afzal Khan was once again being floated as the potential dropout. 

Mr Khan, who has a 8,235 majority, issued a statement on the rumours which failed to deny he would stand down.

He merely said: 'At the last General Election, the people of Manchester Rusholme put their trust in me to represent them to Parliament, and that is the job I am focused on doing.'

Mr Burnham's supporters in the Commons called for any such decision on allowing him to run to be taken by the 40–strong full National Executive Committee, rather than the smaller officers' core, lead by Sir Keir, which blocked him from standing in February's Gorton and Denton by–election.

On Wednesday, one senior source on the NEC told the Mail the feeling is that Mr Burnham's supporters would succeed in their bid.

The Burnham–sceptical member of the committee said: 'On the full NEC, I can imagine he'd win.

'They'll be saying there's a need to 'broaden the debate'.'

Members of the officers' group also have their minds on the upcoming Summer elections to the body, it was said, and would therefore want to avoid making any unpopular rulings about Mr Burnham's future that could impact their chances of re–election.

Left–wing MPs have been in a state of chaos as they tried working out who is best–placed to stop a Wes Streeting victory.

Alongside Mr Burnham, Ms Rayner, Ed Miliband and Lucy Powell were all talked up as potential candidates.

A Labour source said the Left of the party was in 'turmoil' over how to respond if a leadership challenge is triggered before Mr Burnham can get back to Westminster.

'MPs on the Left have taken a long hard look at Angela Rayner and are concluding she is not up to it. She is unpopular in the country and people worry about her chaotic personal life,' said one.

'If it all happens before Andy can get back into parliament then who do they back? That's when Ed Miliband comes into the equation – he's the one who is emerging as the compromise candidate.'

On Wednesday it was claimed that Mr Miliband had the 81 MPs behind him to launch a leadership challenge. though some were said to be on the basis that Mr Burnham could not stand.

Meanwhile, Ms Rayner has kept a low profile, with the former Deputy Prime Minister notably missing from the Commons chamber during the King's Speech and allies suggesting she was 'watching and waiting'.

Long rumoured to be interested in the top job, speculation has grown in recent days that she may not run in a contest as she does not have the support.

She is also still under investigation by HMRC for failing to pay £40,000 of stamp duty on a seaside flat.

One Labour MP who is loyal to Sir Keir told the Mail: 'She can't run. They're all flapping about pretending Burnham can run. He can't.

'They're f*****. They have no Plan B. It's hilarious.'

Another Labour MP said: 'We cannot have her as PM. She's a total liability.'

Instead, Ms Rayner is said to have struck a deal with Mr Burnham in which she backs him for leader in exchange for a top job, such as her former role of deputy prime minister.

Last weekend, she demanded that Mr Burnham be allowed to run for Parliament after saying it was a 'mistake' to block him, that the leadership of our party should put right'.

Mr Burnham was seen at her home at the height of the Mandelson row when Sir Keir's position looked weakest.

Last Saturday, she posted a 1,000–word manifesto–style tweet in which she described the scandal as a 'toxic culture of cronyism'.

Ms Rayner's successor as Labour deputy leader, Lucy Powell, was also talked up as a potential replacement for Sir Keir.

One source on the party's Left warned: 'The one person you do want to keep an eye on and not rule out is Lucy Powell ending up as a compromise candidate.'

'She's incredibly ambitious, and she hasn't got the same flak as all the others.

'Will she be put up as the last–minute offer? She might be.'

Whoever ends up as the Left's candidate will be entirely decided by the timetable of the contest, with Mr Burnham requiring at least until August if he is to pull off his plan.

Allies ambitiously believe Mr Burnham can win a by–election in early June, which could then allow for a handover from Sir Keir Starmer weeks afterwards, before the party conference season.

The source who is in frequent contact with Mr Burnham said: 'He said to me a year ago that May, after the local elections, seems to be the only opportunity.

'He doesn't want to be the Leader of the Opposition after a general election. He feels it's now or never.