Prominent backbenchers Lisa Nandy and Jess Phillips have joined the Labour leadership race with calls to win back trust in former heartlands.
Both mentioned representing areas where once-reliable Labour support was dwindling as they aim to lead the party after its worst general election defeat since 1935.
Wigan MP Ms Nandy, a former shadow cabinet minister, called for the rejection of "the paternalism of the past" and said Jeremy Corbyn's successor must be someone with "skin in the game".
Outspoken Birmingham Yardley MP Ms Phillips confirmed her bid with a call to elect "a different kind of leader" earlier on Friday.
Ms Phillips and Ms Nandy, the third and fourth MPs to enter the race respectively, are both seen as coming from the party's centre-left.
Shadow foreign secretary Emily Thornberry and shadow treasury minister Clive Lewis had already confirmed they would run.
Shadow Brexit secretary Sir Keir Starmer and the current leadership's favourite Rebecca Long-Bailey are also expected to enter the race.
Ms Nandy, who announced her candidacy in a letter to the Wigan Post, said she has "a deeper understanding of what has gone awry in our discredited political system".
She has represented her constituents since 2010.
Ms Nandy became one of the most prominent Labour voices for the result of the EU referendum to be implemented and criticised calls for another public vote.
She said: "Without what were once our Labour heartlands, we will never win power in Westminster and help to build the country we know we can be.
"I have heard you loud and clear when you said to earn that trust means we need a leader who is proud to be from those communities, has skin in the game and is prepared to go out, listen and bring Labour home to you."
She said delivering Brexit should not mean "turning our backs on decency, tolerance, kindness".
Ms Nandy added: "It breaks my heart that in this election so many of you felt you had no choice but to vote for a Tory party that has sent a wrecking ball through our community over the last decade."
Ms Phillips launched with a video on her social media pages detailing how she got involved in community activism in the Birmingham street where she grew up and raised her family.
The long-term critic of Mr Corbyn warned in a separate statement that Labour is in "big trouble" if it cannot win back the trust of its working-class base.
The Remain-backing MP said voters have lost trust in the Labour Party and stressed the need for the prime minister to be challenged with "passion, heart and precision".
She criticised the current leadership for its "woeful response" to anti-Semitism within the party's ranks and for Mr Corbyn's ambiguity on Brexit.
Ms Phillips said: "We have got to be brave and bold and bring people with us, not try and look all ways. Trying to please everyone usually means we have pleased no-one.
"Now is not the time to be meek. Boris Johnson needs to be challenged, with passion, heart and precision.
"We need to recognise that politics has changed in a fundamental way by electing a different kind of leader. More of the same will lead to more of the same result."
The MP, who supported victims of domestic abuse for Women's Aid before entering parliament in 2015, said only "when we are clear and straightforward" will voters again back Labour.
She added: "We're a party named after the working class who has lost huge parts of its working-class base. Unless we address that, we are in big trouble."
Ms Phillips came third in a YouGov survey of the membership behind both shadow business secretary Ms Long-Bailey and Sir Keir, who was clear favourite. Ms Nandy was the last of seven candidates.
But the outsiders will be hoping to boost their profiles with the race not expected to formally get under way until Tuesday before a new leader is installed by the end of March.