The New Yorker interviews Biden “Saturday Night Live” made mad fun over the weekend of comments that President Joe Biden is sharp as a tack “behind closed doors.” The New Yorker this morning offers a peek behind those closed doors. John Harwood tweets that the interview, like his own last fall, “shows talk of his alleged mental decline as utter bullshit.” Evan Osnos writes: If you spend time with Biden these days, the biggest surprise is that he betrays no doubts. The world is riven by the question of whether he is up to a second term, but he projects a defiant belief in himself and his ability to persuade Americans to join him. For as long as Biden has been in politics, he has thrived on a mercurial mix of confidence and insecurity. Now, having reached the apex of power, he gives off a conviction that borders on serenity—a bit too much serenity for Democrats who wonder if he can still beat the man with whom his legacy will be forever entwined. Given the doubts, I asked, wasn’t it a risk to say, “I’m the one to do it”? He shook his head and said, “No. I’m the only one who has ever beat him. And I’ll beat him again.” For Biden, the offense of the contested election was clearly personal. Trump had not just tried to steal the Presidency—he had tried to steal it from him. “I’d ask a rhetorical question,” Biden said. “If you thought you were…