Union leader Len McCluskey will continue to give Jeremy Corbyn his "full support" - after appearing to indicate the Labour leader might step down.
The Unite general secretary appeared to have suggested Corbyn could resign before a general election if the party's poll ratings remained "awful."
But in a series of new tweets, McCluskey described the Islington North MP as a "genuine, decent man fighting for a fairer Britain".
A key ally of Corbyn, 66-year-old McCluskey had said in a Daily Mirror interview that Corbyn and shadow John McDonnell would examine the situation if Labour was still polling badly in 2019.
He had even said that the pair were not "desperate to cling on to power for power's sake."
Those comments then triggered a bitter exchange with McCluskey's Unite leadership rival, Gerard Coyne, who claimed the union chief was acting as Labour's "puppet master".
McCluskey shot back, claiming that Coyne's campaign was being orchestrated by the "failed plotters" who had sought to oust Corbyn.
And after his Daily Mirror interview was published, McCluskey took to Twitter to re-affirm his support for Corbyn.
"Jeremy Corbyn continues to have my full support, he's a genuine, decent man fighting for a fairer Britain - media headlines distort facts!" he said.
In his interview, McCluskey said Corbyn should be given the time to prove himself as Labour leader.
But he added that the situation could change if Theresa May did not call an early election and Labour was still struggling in 2019.
"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," he said.
"The truth is everybody would examine that situation, including Jeremy Corbyn and John McDonnell."