 for him to put to bed the doubts about his candidacy. Senator Michael Bennett, the Colorado Democrat, who briefly ran for president himself, said Mr. Biden had to, quote, reassure the American people that he can run a vigorous campaign against Donald Trump. Senator Patty Murphy of Washington, a senior member of the Democratic leadership team, put out a statement that passed for fighting words, saying that the president must do more to demonstrate that he can campaign strong enough to beat Donald Trump.