Angela Rayner is set to tell the Labour Party it must "win or die" in a fiery speech setting out her bid to be deputy leader.
The straight-talking Shadow Education Secretary, will tell Labour members how she will bring the party together after its catastrophic election defeat as she launches her bid to become deputy leader in her native Greater Manchester.
She will warn against a return to the "vanilla politics" of the past in a nod to the radical overhaul of Labour under Corbyn.
But Rayner, who left school at 16 without any qualifications, will say that Labour should avoid using the language of revolution.
The outspoken MP has been credited with pushing Labour's National Education Service and championing the Sure Start centres introduced by the last Labour government which helped her to go back to education after dropping out to raise her son.
Making her pitch at the Community Centre in the Bridgehall estate where she grew up and brought up her son as a young mum, will say that Labour's call for change must be presented as common sense change people can believe in.
Rayner, who became political through the trade union movement will unveil support from across the party including Shadow International Trade Secretary Barry Gardiner and shadow policing minister Lou Haigh.
Highlighting the scale of the challenge facing Labour, Ms Rayner will point to seats across the UK that, in a matter of years, have gone from “heartlands to battlegrounds” and where people have felt the Party has “lost touch with them”
She will warn: “The gap between generations has never been starker. Our coalition, the foundation of our party, is broken.
“This crisis has been a long time coming and we’ve kept avoiding it. It is the biggest challenge in our history.”
Ms Rayner will go on to say that the next five years will be “the fight of our lives” but one that the entire Labour movement must tackle head on.
She will say: “The quick fix of a new leader will not be enough.
"We must rethink and renew our purpose and how we convince the people to share it.
"Either we face up to these new times or we become irrelevant.
"The next five years will be the fight of our lives and I’m standing here today because I don’t run away from a fight.”
The Shadow Education Secretary was expected to go for the top job but stood aside to help Rebecca Long-Bailey - her close friend and flatmate.
The deputy leader post has been vacant since before the general election , when Tom Watson announced he was quitting Parliament.
Ms Rayner, who is widely considered the frontrunner, is expecting to be challenged by Shadow Justice Secretary Richard Burgon and shadow sports minister Rosena Allin-Khan.
The deputy leadership race has so far been overshadowed by the race to succeed Jeremy Corbyn who announced he was standing down in the wake of Labour's crushing defeat, when the party won just 202 seats - its worst election performance in more than 80 years.
He will stay on in the post until the end of March, while a new leader and deputy and are chosen.
Today the party's ruling NEC will hold a crucial meeting to decide the timings and other details surrounding the contests.
So far Emily Thornberry, Clive Lewis, Sir Keir Starmer, Lisa Nandy and Jess Phillips have announced they are running for the leadership while Ms Long Bailey is expected to announce this week.
