"Any little thing that gives people the opportunity to try and undermine Corbyn and paint the Labour Party as some form of misogynist, anti-Semitic organization is used by these people. It's absolutely wrong," McCluskey has told DW.
In an interview with Tim Sebastian on Conflict Zone, the union boss went on to say, "People like Jeremy Corbyn and me have been out on the streets physically fighting the racists and the anti-Semites. So, I won't take any lessons whatsoever from the right-wing media or right-wing Labour MPs who've never lifted a finger in their lives to oppose discrimination."
Having far outperformed expectations in the snap general election called by Prime Minister Theresa May, Jeremy Corbyn’s Labour Party sees itself more and more as a government in waiting as the Conservatives continue to have public battles over Brexit.
"Labour's job at the moment is to hold the government to account because they're in an absolute mess,” says McCluskey. “Our colleagues over in Europe tell us that their information from their governments tell them that nobody knows what Britain is looking for or wanting at the moment."
But while the Labour Party has its own internal issues over Brexit, its problems with relationsips abroad extend beyond Europe.
As staunch supporters of the late Venezuelan leader Hugo Chavez and successor Nicolas Maduro, McCluskey, along with Corbyn and other allies, have been attacked for hypocrisy and an apparent unwillingness to criticize the human rights abuses perpetrated under both leaders.
"I think what's currently happening in Venezuela is a concern for all of us. And what we're seeking to do is, obviously, try to make certain that the real news, the full extent of what's happening, and the full picture is understood," said McCluskey.
Challenged by Tim Sebastian that this "full picture" was simply pro-government propaganda, the Unite leader said, "We are in favor of human rights and we've called upon the Venezuelan government … to promote the concept."
But in a fiery follow-up exchange, Sebastian questioned why McCluskey had failed to acknowledge reports from credible authorities:
Sebastian: I don't see you quoting Amnesty International or the UN High Commissioner for Human Rights or the European Parliament. I don't see you quoting any one of those.
McCluskey: Tim, what we won't do is jump on the bandwagon that's being whipped up by the hysteria of the right-wing.
Sebastian: Where? Where did you condemn the widespread and systematic use of excessive force against demonstrators in Venezuela?
McCluskey: Tim, you're getting an exclusive. I'm condemning any form of attacks on human rights …
Sebastian: By the government?
McCluskey: By the government.
Human Rights Watch says under Chavez and Maduro the "erosion of human rights guarantees have enabled the government to intimidate, censor, and punish its critics" and "impunity for human rights abuses" persists.
"There are people within the establishment – both the right wing establishment and the Labour party establishment – who have constantly sought to have a proxy war against Corbyn," McCluskey told Conflict Zone.
McCluskey also suspects the UK's domestic security services, MI5, as working to undermine Corbyn's agenda, saying in an interview last year that their role will be uncovered when the relevant files are declassified in 30 years' time.
Asked whether he had any evidence to support the claim, McCluskey told Tim Sebastian that he didn't, but that "the history of the security forces in the British labor movement has been nothing short of disgraceful."
'What is important is winning'
McCluskey's own position as leader of Unite, like his ally Jeremy Corbyn, has also drawn criticism from established figures within his own organization.
In a letter to the Guardian endorsing McCluskey's opponent for the leadership, Gerard Coyne – who was suspended by the union shortly after ballots closed – three former senior officials wrote: "There comes a time when all trade union officials must make way for their successor generation and we believe that time has come for Len McCluskey."
"And I'm delighted I didn't have their support," McCluskey told Tim Sebastian.
Nonetheless, he was reelected as the union's leader, albeit with a much reduced number of votes than in 2013, dropping from 144,000 to 59,000.
McCluskey stressed there was a more important factor than this: "I won. Now what is important is winning."