Vice President Joe Biden, a man with nearly four decades of experience in politics, has not been taking lightly his preparations for his debate against Rep. Paul Ryan, R-Wis., holding practice sessions and perusing briefing books in recent months.

Now, in the wake of President Barack Obama’s widely panned performance last week in his first debate against Mitt Romney, the stakes for Biden are suddenly higher than ever. In the Oct. 11 vice-presidential debate he must not only avoid making any gaffes but also try to puncture his Republican opponent’s arguments on taxes, entitlement reform and deficit reduction, something Obama was criticized for failing to do last week.

The pressure on Ryan has risen as well. Romney greatly exceeded expectations, appearing both presidential and in command of the debate stage. Ryan, who has never before debated at the national level, must prove that he is potential presidential material – while also defending the numbers that Romney put forth last week, especially on tax cuts.

Both sides are offering sky-high predictions for the other team.

“There’s a lot on the line,” said Rep. Jason Chaffetz, R-Utah, a chief Romney-Ryan ally. “President Obama failed to defend his record and could not articulate a vision for the future. So I think that challenge now falls to Vice President Biden.”

Bill Burton, former White House deputy press secretary and co-founder of the Democratic super PAC Priorities USA, argued that the burden is actually on Ryan.

“Ryan is going to face pressure to explain some of the dishonest claims he and Romney have been making, especially on things like Medicare, taxes and the auto industry,” he said.

One point on which both sides appear to agree is that Biden is likely to be more aggressive in his faceoff against Ryan than Obama was debating Romney.

Biden told reporters last week that he’s been “studying up on Congressman Ryan’s positions on the issues.”

“I just want to make sure that when I say these things, I don’t have the congressman (say), ‘No, no, no, I don’t have that position,’ or ‘That’s not the governor’s position,’ ” Biden said.

Ryan said he believes Biden will be an aggressive opponent.

“I expect the vice president to come at me like a cannonball,” Ryan told the conservative Weekly Standard. “He’ll be in full attack mode, and I don’t think he’ll let any inconvenient facts get in his way.”

Both White House contenders have been deeply engaged in debate preparations even as they maintain busy schedules on the campaign trail. For Biden, that has meant squeezing in time for debate preparations while visiting with his family in Delaware, as he did one weekend earlier this month. For Ryan, it’s meant practice sessions in Washington, as well as his hometown of Janesville, Wis.

Biden who kicks off an intensive “debate camp” this week in Wilmington, Del., so far has engaged in two mock debates with Rep. Chris Van Hollen, D-Md., who is playing the role of Ryan in the vice president’s practice sessions.

Ryan on Friday wrapped up a three-day debate camp in southwest Virginia; prior to that, he had held three mock debates with former U.S. solicitor general Ted Olson, who is playing the role of Biden. Kerry Healey, who served as Massachusetts’s lieutenant governor when Romney was governor, has been playing the role of moderator Martha Raddatz of ABC.

As during Biden’s faceoff four years ago against former Alaska governor Sarah Palin, there’s also the matter of the age and stature gap between the two candidates. Biden is 69, has run for president twice and served in the Senate for 36 years. Ryan is 42, has served in the House for 14 years and will make his first appearance on the national debate stage on Thursday in Danville, Ky.

Both sides sought to downplay the importance of that gap. Some Democrats dismiss the notion that the stakes are raised for Biden – and counter that the onus is on Ryan not only to defend Romney, but also to prove that he himself is ready for prime time.

“I think the pressure in my book is on Paul Ryan, because he’s got to demonstrate that he has what it takes to be president of the United States,” said Democratic strategist Doug Thornell.