Unite general secretary Len McCluskey speaks with passion about his crusade for a fighting union and a bold Labour Party as we meet at the union's London HQ.
Asked why he has put himself forward two-and-a-half years early for election to a further five-year term, the 62-year-old proclaims: "I'm not leaving the battlefield.
"I want to stand shoulder to shoulder with our members, and I am going to hound this government."
He warns of a danger that some of the Labour leadership would be tempted to ignore the union's demands for radical policies if they thought he would be leaving the job around the time of the next general election.
"There'll be individuals saying to Ed Miliband, don't worry about what Lenny's got to say - he won't be here.
"I want to be able to say to Labour leaders that I'm going to be here after the election to ensure that if you are back in government, then you actually deliver on the commitments you've given us."
Bluntly, he predicts that Ed Miliband will face defeat at the next election if he simply pursues a policy of "austerity-lite."
People are desperate for a radical alternative, and Labour activists are looking for inspiration, McCluskey says.
The party relies on foot soldiers from trade unions as well as funds, he points out.
"They rely on our activists going out and knocking on doors. They've got to be inspired to do that."
He praises Miliband's new plan for setting up regional banks linked to a proposed British Investment Bank.
"This is something we have been pushing for, and it's a very welcome development."
But he also warns that the Labour Party does not have "a God-given right to exist," adding that it can only thrive if it is the voice of working people and organised labour.
"If it fails to be that voice, given that one of Unite's central objectives is to have a voice in the political arena, it would mean that we would have to look elsewhere.
"If Labour want to adopt a different cloak, then there is a huge question mark.
"This is the watershed, the crossroads that I believe Labour is currently at."
He contemptuously dismisses Prime Minister David Cameron's sneer about Miliband having "dinner after dinner" with "dinosaur" trade union leaders to raise funds.
"I don't so much as have a sandwich with Miliband, let alone dinners," ripostes McCluskey.
"That's never happened, although I meet him of course - but not that regularly.
"It's my job to try and influence Ed and the leadership of the Labour Party as they begin to construct their programme to take to the British electorate.
"One thing that does amuse me about the right-wing media and the Conservatives is that they are always going on about how irrelevant trade unions are.
"Well, if we're that irrelevant, why do they keep attacking us? It was also a preposterous attack from a PM who had to sack his own party treasurer in a dinners-for-donors scandal.
"Everywhere I go, our activists say to me, why are we giving so much money to the Labour Party?
"Let me just put this on the record. I said when I became general secretary that I wouldn't give Labour a single penny over and above our membership fee, our affiliation.
"And that's what we do. We affiliate to Labour because we're part of Labour and that's our membership fee. I don't give any money over and above that.
"This is the position until such time as we see the Labour Party beginning to listen to us."
McCluskey warns that the crisis of capitalism is taking a form that nobody has experienced before - different from the depression of the 1930s.
"Neoliberalism has crashed onto the rocks, but the problem is that while the Tories and the ruling elite are trying to stick the ship back together again with glue and spit, we also have important figures in the Labour Party who are trying to stick it back together."
I ask what difference he can make by staying on for a further full five-year term.
He points to "huge support" he has received from every sector of the union and from different factions, with over 1,000 branch nominations and the backing of every single national officer.
"Since I took over as general secretary, my task has been to unite the union, because there were divisions," he says.
"I believe I've been successful in creating a unity of purpose.
"We've initiated a whole string of policies that actually need time to embed themselves into the union, and represent a change of culture.
"Whether it be our 100 per cent campaign to strengthen our already organised workplaces, or our campaign for community membership, or our political strategy.
"These all take time. And we don't want to have a clash between an election for general secretary and a general election.
"Divisions would open up and people would quite understandably jockey for position.
"That would fracture the fragile unity we have built. It is fragile because the union is still in its infancy.
"It would not assist the Labour Party and the media would present it in a very nasty fashion."
McCluskey explains that he is still working hard on creating a new "Unite culture" within the young union, which carries the legacy of its formation from Amicus, the T&G and other unions.
"Some of our officers may have been appointed 15 years ago to do a specific job in a specific way. But they now need to do this job in a different way.
"My task is to change the union's culture and make certain that Unite stands for true lay member democracy and accountability.
"The union's officers must absolutely clearly understand the principle of a fighting-back union - a union always on its members' side.
"So my clear message to our activists is that they need to take ownership of Unite. They need to feel their voice is being heard.
"We've created a £25 million strike fund, and strike pay has been doubled to £30.
"I have never repudiated a single strike since I became general secretary. I want our members to know that we're with them every inch of the way.
"Our new Leverage Strategy has helped win disputes, and we've gained over 62,000 extra recruits in 15 months.
"We resisted the construction employers' attempt to break away from national agreements - and they collapsed like a pack of cards.
"We've won disputes with Honda, a major multinational company which suspended our convener and was ready to derecognise us. We won, our convener is back, our membership has trebled and the managers involved were sacked."
McCluskey also points to some successes for the union's political strategy of aiding selection of parliamentary candidates sympathetic to the union's values.
Among his campaigning highlights this year are the launch of the Campaign for Trade Union Freedom next Saturday, the People's Assembly on June 22 and the Durham Miners' Gala. He will speak at them all.
"These are hugely difficult times," he adds, predicting an upsurge of strikes, direct action and civil disobedience.
"That's why I'm not going off to retire and sit in a rocking chair. I want to be fighting with our members all the way."
Len McCluskey urged Ed Miliband and other leading Labour figures to give more recognition to the important role of the Morning Star, even if they did not agree with all its editorial policies.
"The Morning Star is an authentic voice of organised labour, and also reflects the aspirations and concerns of ordinary people and the realities of their lives.
"If Ed and the Labour leadership want to re-connect with ordinary people, then they should use every vehicle possible. And that certainly includes the Star."
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