 Right beside him was his newly anointed running mate, J.D. Vance, the Ohio senator who closely adheres to Mr. Trump's political vision. He was asked on Fox News how he saw the role. The president can't be everywhere. Even Donald Trump can't be everywhere. So you've got to be a person he can trust, he can rely on to actually advance the agenda. That's the most important job. Of course, if something, God forbid, happens, you've got to be ready to step into that office. That's one of the most important roles of the vice president.