Obama needs Biden to be merciless at the debate or something
That means that Biden not only has to take on Ryan, but more crucially, if by proxy, Romney.
He has to: rebut Romney’s unanswered attacks, such as the notion that federal job-training programs are wastefully duplicative; call Romney out for his brazen effort to sound like a bipartisan moderate, after a year of industrial-strength sucking up to the Tea Party; tout accomplishments of the Obama-Biden administration in ways the president mysteriously failed to do; and better explain to voters why the next four years would be better in Democratic hands than they would be under the GOP.
Is Biden up to it?
No one knows what will happen Thursday, but in theory, yes.