Sullen isn’t presidential. Don’t look like you’re at the dentist’s while waiting to zing him as a toothless tiger. And no goofy Biden grins. Fascinated, slightly amused disbelief would be good.
Show friendly but firm confusion about his flip-flops and evasions. Which Romney of the oh-so-many is answering a particular question? And slide in a capsule history of his U-turns on health care, gays or whatever.
Stand tall and take charge as Commander-in-Chief while deploring politicizing of the American deaths in Benghazi and defending Hillary. Chivalry and subdued outrage are the ticket.