Democratic presidential candidate Bernie Sanders has denied that he "disagreed" with rival Elizabeth Warren when she said a woman could win the US election in 2020.
Ms Warren claims Mr Sanders, who she is battling for the chance to face Donald Trump at the polls, made the comment in a private meeting in 2018.
Ms Warren, in a statement released on Monday, said: "Among the topics that came up was what would happen if Democrats nominated a female candidate.
"I thought a woman could win; he disagreed."
A senior adviser to Mr Sanders said that "those conversations can sometimes get misconstrued", while the candidate himself said he wholeheartedly believes a woman could win.
"Do I believe a woman can win in 2020? Of course! After all, Hillary Clinton beat Donald Trump by three million votes in 2016," he said in a statement to CNN.
He added that he did state that he believed President Trump would "weaponise" whatever he could against Ms Warren.
The feud marks a heated change of pace in the Democrat's primary campaign, which will determine the nominee who will challenge President Trump in November's election.
Voting in the Democratic Party contest begins next month.
Mr Trump could not resist a dig at the Democrats, tweeting: "Bernie Sander's volunteers are trashing Elizabeth 'Pocahontas' Warren.
"Everybody knows her campaign is dead and want her potential voters. Mini Mike B is also trying, but getting tiny crowds which are all leaving fast.
"Elizabeth is very angry at Bernie. Do I see a feud brewing?"
