The two progressive U.S. senators, Warren and Sanders have hit heads in their nomination campaign trail.
Tensions rose again after a CNN report revealed details of a meeting where Sanders told Warren he didn't believe a woman could beat Trump.
Warren confirmed the report and said in a statement on Monday "I thought a woman could win; he disagreed." Trump backed Sanders at his rally, saying he did not believe Sanders would suggest a woman could not win the 2020 election.
"But Bernie said - according to her Bernie said - and I don't believe that Bernie said this cause I don't know him.
I don't particularly like him.
He's a nasty guy.
But I don't believe he said it.
It's not his deal."