Burden on Biden to be better than his boss

Vice President Joe Biden must be everything President Barack Obama was not: energetic, aggressive and concise. Rep. Paul Ryan must meet the moment and keep things going Mitt Romney’s way. And voters must figure out whether an evening with the running mates even matters to them at all. In an election running short on time for turning points, tonight’s vice presidential debate has the potential to be one. But history suggests otherwise. Just as vice presidents play a secondary role, so do the debates between the No. 2 candidates, particularly with two face-offs remaining between the men who would lead the nation. What matters this time is which candidate delivers a more compelling message about helping Americans get jobs or improve their economic standing. That makes this debate significant. The impression it leaves will help drive the political narrative for the next five days, until Obama and Romney debate one another again. Any signature moment or performance tonight—electric or awful—could alter the spirits of their campaigns and the TV ads they run—and, of course, influence the millions of people watching at home. The debate starts at 8 p.m. Read the full story here.