An official with the Unite union is to apply for the post of general secretary of the Labour Party.
Jennie Formby said she would be proud to be the first woman in the post in a generation, and only the second ever.
She paid tribute to Iain McNichol, who announced his resignation last week.
In a statement, she said Labour was more united under Jeremy Corbyn's leadership, adding: "The general secretary of the party needs to be someone who can build on that unity to mobilise and organise the entire party and the wider labour movement behind a Labour victory at the next general election whenever this callous and crumbling Government decides to call it.
"Labour's strength rests on three pillars - the support of millions of voters, an individual membership far larger than that in any other British political party, and our link with our affiliated trade unions. I believe I am well-placed to help our party build on all three.
"My service as a party member for 40 years, as a member of the National Executive Committee for the last seven, and as a senior official of my union in industrial, political and administrative posts, has given me the breadth of experience to lead the whole party in meeting the challenges and seizing the opportunities ahead.
"I will work with all parts of the movement to ensure that the party democracy review empowers the party membership, opens up policy-making, and ensures democratic best practice throughout.
"I will ensure our exciting new community organising initiative is developed to help entrench Labour in the communities we serve and win the seats we need at the next general election."
Ms Formby said she stands for a tolerant and welcoming party, with no place for anti-Semitism, racism, misogyny or any form of abuse or intimidation, and a party in which complaints are handled fairly and speedily.