A supporter of Keir Starmer’s leadership is to launch a new attempt to lead Labour’s most generous union backer, the Observer can reveal. Gerard Coyne, who was narrowly defeated by current leader Len McCluskey in a bitter battle for the Unite leadership in 2017, has announced that he will aim to become its new general secretary when a contest begins later this year. The battle over who leads Unite is an important one for Starmer. McCluskey, who will formally step down next year, was one of Jeremy Corbyn’s closest allies and has already attacked the current Labour leader over his decision to pay damages to ex-staffers who claimed the party had not dealt with antisemitism. Unite has also cut its support to Labour in the wake of the decision. In a statement to the Observer, Coyne said: “Unite the Union will hold its election for general secretary this year. When it does, after receiving much encouragement and support, I will put myself forward as a candidate. I am offering a progressive vision for Unite and its members that embraces the digital age and focuses on the members and their needs in a changed work environment. “Unite needs real change. I believe the culture needs to change, and that our union must modernise in order to be successful, effective and relevant. We must do far more to protect our existing members, organise in growing sectors of the economy, and we must respond far more decisively to the post-Covid world of work.” Coyne was sacked in June 2017, three months after standing against McCluskey for the union’s leadership. While McCluskey won 59,067 votes (45.4%), Coyne won 53,544 (41.5%). This time around, Coyne’s allies believe he may be helped because there are two candidates fighting for support for the union’s left. Coyne added: “I stood in the previous election for general secretary and very nearly won. I believe the past few years have shown I was right to stand and hold to account the leadership of Unite for its attempts to run the Labour party. Keir Starmer has displayed a sure touch on the major issues he has faced in his first year, and I think he should be given the support to help Labour win power in the interests of working people.” It comes with the new leader of another Labour-affiliated union set to be unveiled on Monday. The frontrunner to be named the new leader of Unison, the UK’s biggest union, is also a figure said to be broadly supportive of Starmer’s leadership. Christina McAnea, one of the union’s assistant general secretaries, faces a challenge from counterpart Roger McKenzie, who has been backed by Corbyn. A friendly set of union general secretaries could be a major boost for Starmer as he seeks to develop his leadership this year. McCluskey has already warned Starmer over any attempt to shift to the right or drop some of his leadership pledges that borrowed heavily from Corbyn’s last election manifesto. Unions still have huge influence in Labour’s party conference and its ruling body. They also provide large amounts of funding for the party. Unite gave Labour £3m in the run-up to the last general election. The 2017 battle for the Unite leadership was hugely divisive and subsequently saw Coyne suspended from the union. Several Labour MPs who opposed Corbyn’s leadership had been supporting him. Coyne later dropped an unfair dismissal claim. However, his allies believe he now has a real chance of seizing Unite’s leadership, with two prominent candidates vying to win support from the union’s left wing. Howard Beckett has been highly critical of Starmer’s leadership so far. Last year, he led a walkout by left figures from a meeting of Labour’s national executive committee in protest at what he described as “Keir Starmer’s factionalism”. Steve Turner, another current union official, has taken a more emollient tone towards Starmer, but is also on the left. He narrowly beat Beckett to the endorsement for the United Left faction of Unite.