Bridget Phillipson has confirmed she is standing to become deputy leader of the Labour Party.
The Education Secretary, who was first elected to the House of Commons in 2010, became the first Cabinet Minister to enter the contest.
In a statement, the Education Secretary said: "I am a proud working-class woman from the north east.
"I have come from a single-parent family on a tough council street, all the way to the Cabinet, determined to deliver better life chances for young people growing up in our country.
"I’ve taken on powerful vested interests in the education sector - and even as they threw everything at me, I have never taken a backwards step. I will bring that same determination to every battle ahead of us.
"Because make no mistake: we are in a fight. We all know the dangers Reform poses to our country.
"But not only am I ready for it: I’ve proven we can do it. I’ve shown we can beat Farage in the north-east, while staying true to the Labour Party’s values of equality, fairness and social justice.
"With me as deputy leader, we will beat them right across the country and unite to deliver the opportunity that working people across this great country deserve."
Bridget Phillipson has thrown her hat in the ring to become Angela Rayner's replacement
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Ms Phillipson joins hard-left Bell Ribeiro-Addy as the only two declared candidates so far.
Ribeiro-Addy, a privately educated life-long socialist who last year demanded Sir Keir Starmer take action on slavery reparations, publicly criticised Labour's leadership over the contest's timeline.
After confirming her candidacy, the Clapham & Brixton Hill MP said: "There is a clear attempt underway to rush the deputy leadership contest.
"After the missteps of the past year, we need a proper debate about the future direction of our party; not a coronation.
Bell Ribeiro Addy MP is the only other candidate so far
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"It must be a full and fair contest with a genuine Left candidate on the ballot paper."
However, other Labour MPs are expected to declare their intention to stand later today, with PLP nominations opening today.
Ex-Shadow Attorney General Emily Thornberry looks poised to mount her bid later today after appealing to Labour MPs last night.
There have been growing calls for Labour's next deputy leader to be both a woman and from outside of London.
Experts have told Sir Keir Starmer that the next deputy leader should be both a woman and from outside of London
| PASpeculation grew last night that Local Government Minister Alison McGovern would stand as No10's stalking horse against any hard-left challengers.
Asked at the Trades Union Congress (TUC) conference on Monday whether she planned to run, Ms McGovern said: "You’re just going to have to hold your horses."
Ms Phillipson will also address TUC delegates in Brighton later today.
However, Sir Keir's allies entering the race threaten to turn the contest into a referendum on the Prime Minister's premiership.
Bridget Phillipson could serve as a vital ally to the Prime Minister
| PANew Home Secretary Shabana Mahmood yesterday ruled herself out of the contest, instead insisting that her efforts will be spent curbing the number of migrants crossing the Channel.
A new poll by Find Out Now found that Deputy Prime Minister David Lammy received the backing of 22 per cent of Labour members.
Ms Thornberry secured second-place on 18 per cent, with Health Secretary Wes Streeting in a distant third on 13 per cent.
Rosena Allin-Khan, Louise Haigh, Lucy Powell, and Sarah Owen all secured single-digit support.
Meanwhile, while just one per cent endorsed Ms Ribeiro-Addy's bid, Find Out Now found that one-in-four Labour members were unimpressed with the list, selecting other or none of the above.