 Joe Biden is aggressively fighting back against his critics and insisting he will not step aside. In a call with top party donors, he said it was time to put the focus back onto Donald Trump and, as he put it, attack, attack, attack. Mr. Biden has many allies in his party who publicly say that they do support him staying in the race, but the list of Democrats expressing their doubts is getting longer. Mr. Biden insists he will not be pushed aside by the party's elites, wealthy donors or the press.