A n emerging rift between Melania Trump and Hunter Biden escalated Thursday when the son of former President Joe Biden issued an expletive-laden response to the first lady's demand that he apologize for an allegation he made about her alleged prior ties to convicted sex trafficker Jeffrey Epstein.

Jeffrey Epstein did not introduce Donald and Melania Trump, the president said, after the first lady threatened to sue Hunter Biden for $1bn for making the claim.