There was a similar message from Sharon Graham, the leader of the Unite union – though her warning to Labour has financial as well as political consequences.
At her own union’s conference in the summer, delegates voted overwhelmingly to re-examine its relationship with Labour.
She has now told the BBC that at a future Unite conference, there will be an opportunity to sever a long-standing link which is worth around £1.3m a year to Labour.
She said: “Instinctively, workers don’t feel that Labour is on their side. We will be giving our members the opportunity to vote on whether to remain part of Labour when the time comes.
“If that vote was today, I think they’d vote to disaffiliate. There’s no doubt about that in my mind.”
Graham predicted that Reform UK would be the chief beneficiaries if Labour failed to improve standards of living. She argued that “unless Labour do something quite radical”, then “they are going to find themselves in huge difficulty.”
She added: “They’ve got about a year to get this right. And if they don’t do that, people will start moving away from them, and I don’t believe they’ll go back.”
Nowak also had a message for Reform’s leader, Nigel Farage: “Ignore your wealthy backers and vote for the Employment Rights Bill.”
He asked Farage to come clean about whose side he’s “really on”.
“You’re not representing working people – you’re selling them out,” he said.
Labour has said it is delivering the biggest uplift in workers’ rights in a generation and that wages are now rising faster than prices.
Prime Minister Sir Keir Starmer has said that the next phase of government will focus on “delivery, delivery, delivery” of its promises.
The BBC has contacted Reform and the Conservative party for comment.