Angela Rayner has claimed she is neither a “Corbynite” nor in the mould of any other past Labour leader as she officially launched her campaign to become party deputy.

The shadow education secretary said she would not be pigeonholed politically despite working closely with the Labour leader since she was elected to parliament in 2015 and being one of the most senior female figures in his team.

Rayner is believed to be among the frontrunners to replace Tom Watson.

She said: “I don’t consider myself to be of one political persuasion or another. I’m not a Blairite, I’m not a Corbynite, I’m not a Brownite. I’m an Angela Rayner – a member of the Labour party who has various different opinions on lots of different things just in the same way MPs and other party activists would.

“I hate it when people try and pigeonhole me.”

At her launch in a community centre on the estate where she grew up in Stockport, Greater Manchester, she said female politicians were often asked what kind of male politician’s style they might try to emulate.

On whether the expected leadership candidate Rebecca Long-Bailey – who is also her flatmate – is “continuity Corbyn”, Rayner said she “took offence on her behalf”. And she said: “One thing I know about Becky and you will know soon, if you don’t already, is she is her own woman.”

Asked how she defined her own politics, Rayner said: “I am definitely a socialist and I’m proud to be one. I am actually proud that you can actually say that because I think at one time saying that you’re a socialist meant you were some sort of loony left which is a term that I don’t like.

“In fact that was levelled at me during the general election by a Conservative MP, which I think is quite offensive to people in our movement.”

Rayner said the party faced an existential challenge in the aftermath of the general election defeat. “As a party we face a choice. Win or die. And I fight to win,” she said.

She said she accepted her share of the blame for Labour’s Brexit position that had confused both remainers and leavers, including members of her own family.

“I have to accept responsibility. We all must have to accept some responsibility in the Labour party because we were divided as a party and divided parties do not win general elections.

“Time and time again we had people saying they felt patronised. Members of my family were very angry with me and I couldn’t go to the pub or school gate without someone wanting to tell me about what they thought we were doing.” She said the party now had to draw a line in the sand.

Speaking in the Bridge Hall estate in Stockport, where Rayner grew up and raised her son Ryan after giving birth as a teenager, she said was proud to return there to make her pitch.

“I wanted the young girls in particular on this estate to know that they are me, and I am them, and that was so important to me that I came back here and acknowledged the role this estate has had on making me the person I am today,” she said.

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Rayner said she would vote for her flatmate, the shadow business secretary, Rebecca Long-Bailey, if she decided to run for leader, which she is expected to do in the coming days.

The pair, who both had prominent roles under Corbyn, are expected to form an effective joint ticket to appeal to his supporters and those on the left of the party.

“I will be quite straightforward: I will be voting for my friend Rebecca Long-Bailey if she stands for the leadership,” she said.

She explained why she was not standing for the position herself, saying: “I’ve been an organiser all my life and I consider some of my key skills of bringing that unity to our party and taking it forward. I can deal with problems that we face. I can deal with tough questions and I can face down anyone who thinks it’s OK to bully and abuse anyone in our party. I think I can do that as deputy leader.”

“It is no secret for years me and Rebecca Long-Bailey have been good friends and I wasn’t going to stand for leader and allow everyone in the media and everyone outside saying ‘who is the better woman?’.”

She said the next five years would be “the fight of our lives” but one the entire Labour movement must tackle head-on.

The cross-party support Rayner has gained at this early stage is being seen as a major advantage while other candidates are still ringing around seeking endorsements from colleagues.