WASHINGTON -- Four years ago, Joe Biden was careful not to appear overly aggressive in his vice presidential debate with Sarah Palin, then a newcomer to the national stage.
Now, as he prepares to debate Paul Ryan, a 14-year House veteran and the top Republican budget writer, Biden is less concerned about looking like a bully.
"I think he is going to play hardball," said former Michigan Gov. Jennifer Granholm, who played Palin in debate preparations in 2008 but is not involved this year. "He won't have to worry about pulling punches."
Vice presidential debates typically don't matter as much as presidential faceoffs, but representatives of both parties say the stakes for tonight's clash in Kentucky are higher because of President Barack Obama's lackluster showing in last week's first presidential debate. The 90-minute debate begins at 8 p.m.
A strong performance lifted Republican challenger Mitt Romney, helping him cut into Obama's lead in key battleground states.
Officials in both parties expect the vice president will be notably more aggressive than Obama, repeatedly taking the fight to Ryan as Democrats try to regain their footing.
"Obviously, what we expect is the vice president's going to come at me like a cannonball," Ryan said this week.
The 42-year-old congressman must overcome a lack of foreign policy expertise and experience in national debates, although Democrats praise his encyclopedic grasp of budget details and ability to think on his feet.
"Paul Ryan is an inside Washington guy, smart and wonky. He knows the budget better than anybody," said Granholm.
Biden is likely to press Ryan to defend Romney's proposals on taxes, Medicare and spending -- and seize any opportunity to tie Romney to a House Republican budget written by Ryan. Democrats say the GOP budget contains severe spending cuts unacceptable to most voters.
Rep. Chris Van Hollen of Maryland, the senior Democrat on the House Budget Committee, of which Ryan is chairman, said his colleague "has a fundamental choice to make" in the debate.
"He can either come clean about the negative consequences of the Romney-Ryan budget and tax plan, or he can continue to hide the ball like Mitt Romney did the other night," said Van Hollen, who is playing Ryan in debate preparations.
An effective performance by Biden, a former senator who essentially made a career out of debating colleagues, could help quell nervousness among Democrats.
Democrats say Biden brings an authenticity that voters relish.
"If you want someone who gets middle-class America and gets family in America, Joe Biden is absolutely the best person you can find," said Sen. Chris Coons, D-Del., who holds the Senate seat Biden had for more than three decades.
Biden, 69, has participated in numerous debates, both as a presidential and vice presidential candidate, and has tended to be more disciplined in those matchups than on the stump.
Biden said he is looking forward to the debate. He has been closeted in his hometown of Wilmington, Del., since Saturday for practice sessions and prep work with his staff and top advisers.