UNITE leadership challenger Gerard Coyne is being “scripted” by Labour rightwingers for a “political project to bring back Blairism,” Len McCluskey said yesterday.

The Unite general secretary, who has stepped down a year early to seek re-election to the top job, hit back after Mr Coyne accused him of acting as “Labour’s puppet master” by saying that his rival’s comments “pander to the worst anti-Labour stereotypes of the media.”

Mr Coyne, currently the general union’s West Midlands secretary, has repeatedly accused Mr McCluskey of prioritising support for Jeremy Corbyn over industrial relations.

Mr McCluskey told yesterday’s Daily Mirror that Unite’s support for Labour and Mr Corbyn was not uncritical. He said the party leader and shadow chancellor John McDonnell were “not egomaniacs” and suggested they would not “cling onto power for power’s sake” if opinion polling was still “awful” in 2019.

But Mr Coyne said this amounted to issuing an “ultimatum” to Mr Corbyn.

“It is not in the interest of Unite’s members that the general secretary should spend so much of his time and their money playing politics,” the challenger said in a statement issued to the press.

Mr McCluskey, who is backed by the union’s United Left faction, said the “outburst” was “not an attack on myself as much as on our lay leadership and rank-and-file activists.”

He said Mr Coyne’s assertion that he had personally taken the decision to support Mr Corbyn in the two recent Labour leadership elections was misleading, pointing to the endorsements of Unite’s lay structures.

“Unite’s democracy would not be safe in Gerard Coyne’s hands,” he warned.

“These unscrupulous remarks show that Gerard Coyne’s campaign is not being driven by concern for Unite and its members’ interests.”

Mr McCluskey also connected Mr Coyne’s campaign, which is supported by right-wing faction Labour First, to “failed plotters in the Parliamentary Labour Party” who would use Unite as “collateral damage in their political project to bring back Blairism.”

“Unite is electing a general secretary, not a politicians’ puppet,” he added. “I urge Gerard Coyne to raise the tone of his campaign and focus on the workplace issues which Unite members care about.”

Mr McCluskey is also being challenged by Fujitsu Manchester rep Ian Allinson, who is supported by the far-left RS21 group.