Len McCluskey, the head of Britain's biggest trade union Unite, has voiced concerns over Labour losing ground to Ukip. "We need to expose what Ukip stands for; not just anti-foreign – anti-workers' rights, their hidden agenda on the NHS and welfare state.
"But it will only work if ordinary people believe Labour is listening to their concerns and has solutions."
The union leader, who is standing for re-election as general secretary of Unite, says he will continue to tackle "bullying bosses and bad employers".
He added: "We are fearless in defending ordinary working people."
McCluskey believes that Labour leader Jeremy Corbyn needs more time to prove himself.
The head Unite spoke about Labour's chances in the 2020 General Election. "Let's suppose we are not having a snap election. It buys into this question of what happens if we get to 2019 and opinion polls are still awful.
"The truth is everybody would examine that situation, including Jeremy Corbyn and John McDonnell."
He spoke to the Mirror about the personalities of the party leader and shadow chancellor: "These two are not egomaniacs, they are not desperate to cling on to power for power's sake."
Another close ally of Corbyn, Shadow Home Secretary Diane Abbott, told BBC1's Andrew Marr Show: "I would say to you that reports of the Labour party's demise are much exaggerated. We are the largest social democratic party in Europe. And that huge surge in membership is due to the current leadership."
In Corbyn's New Year message, he vowed to challenge "extremely negative messages" from Ukip.
"I will challenge UKIP on the basis that Ukip attacks minorities who run our health service, offers to privatise the health service but doesn't offer to build any houses, doesn't offer to deal with the issues facing communities and doesn't do anything to challenge the appalling underfunding of local government, particularly in the poorest areas," he said.