V.P. Joe Biden among prominent speakers at DNC Thursday

CHARLOTTE, North Carolina (CNN) -- Joe Biden has had many big moments in his long political political career, but Thursday's speech setting up Barack Obama's presidential acceptance speech was one of his biggest.

Biden has as much at stake as his boss. And he had a tough act to follow after former President Bill Clinton delivered a rousing address Wednesday, one jam-packed with full-throated endorsements of the current president.

But while he's been criticized for his gaffe-prone tendencies, Obama's campaign maintains the vice president is a key asset on the campaign trail -- and political observers largely agree. The former six-term senator from Delaware is known for his appeal to blue-collar, left-of-center Democrats, a crucial voting bloc Obama needs to shore up support for November.

And Biden, like Clinton, knows how to be in the spotlight.

"You can say lot of things about Joe Biden, but you shouldn't underestimate him. He's a guy who has a lot of experience. He's a guy who knows how to step up and give a speech," Rolling Stone executive editor Eric Bates said Thursday on CNN. "And he knows how to debate."

A Pew poll released last month showed Biden with low popularity: 27% of respondents said he has done either an "excellent" or "good job" as the president's number two, while 56% said he does only a poor or fair job.

Among Democrats specifically, 51% said he has done an excellent or good job, while 36% said he has performed poorly or fairly. The numbers aren't entirely surprising, given that his main role on the campaign trail is to lead the offensive against Romney.

But Biden, with the largest audience he's had in a while, will have a chance to touch up his image and may try to remind voters of the charm and likability he's been known for in his more than three decades of politics.