Barney Jopson and Robin Harding:

The issue is high on the US political agenda ahead of November’s midterm elections and Mr Trumka – a mustachioed former coal miner and scourge of America’s wealthiest “1 per cent” – is using it to bring new life and new allies to his organisation. “The public is in front of the policy. They’ve been talking about this before [Thomas] Piketty’s book came out,” he says, referring to the unexpected bestseller on inequality.

Stagnant wages have contributed to rising wealth disparity and Mr Trumka, who became AFL-CIO president in 2009, has underscored that its mission is fighting for higher pay. “Every place I go, that’s all people talk about,” he says. “They really don’t talk about the deficit or the Federal Reserve. They talk about wages, and how they’re stretched, and how they’re losing ground all the time, and how their kids’ college loans are eating them alive.”
Beyond the minimum wage itself, Mr Trumka lobbies President Barack Obama and Congress on a range of issues – including trade, immigration and criminal justice – with policies that he says would lift private sector pay, or at least stop corporate executives from forcing it down.