Attorneys representing President Joe Biden's son Hunter Biden are threatening to sue Fox News for violating "revenge porn" laws and publishing since-discredited bribery allegations as part of a scheme to "paint him in a false light," according to a letter obtained by ABC News. The letter, which Hunter Biden's counsel transmitted to attorneys at Fox News last week, includes a request for the conservative news outlet to "preserve all documents potentially relevant to the allegations in this letter" -- a common precursor to litigation. "We anticipate that litigation against FOX ... is imminent," the letter says.