WASHINGTON - US Vice-President Joe Biden is "fired up" about his upcoming debate with Republican vice presidential nominee Paul Ryan, the reelection campaign of President Barack Obama said on Thursday.

Campaign spokeswoman Jen Psaki told reporters that Biden "is pretty fired up and ready to go this evening for the debate." She said that at the debate, Biden's "number-one goal is to lay out the choice for the American people."

"It's obviously a big audience, as any of these debates are, and it's an opportunity to speak directly about the differences between the candidates and the tickets and the positions they represent," Psaki added.

Biden will face off with Ryan at Centre College in Danville, Kentucky on Thursday evening.

Vice presidential debates traditionally don't carry the same influence as presidential debates in elections, but after Obama's lackluster performance in the first presidential debate with Mitt Romney last week, Biden is under pressure to do well in this debate. Obama called Biden in the day to wish him good luck, according to Psaki.

In what might be good news for Biden, Ryan is heading into the debate with some negative exposure. The Time magazine published a photo series on its website on Thursday, which showed Ryan in workout gear posing in a gym with dumbbells. The photos, taken in December 2011, were considered "unflattering" by some conservatives.