For the third time in as many presidential election cycles, the vice-presidential debate on Thursday night will showcase two candidates who came of age -- both personally and politically -- in different eras.
The generational gap between 69-year-old Joe Biden and 42-year-old Paul Ryan may not be at the forefront of either campaign's debate practice sessions, but it is could have an impact on "perception battle" from the moment that the two men take the stage.
In the 2004 VP debate, the age difference between John Edwards and Dick Cheney was a relatively modest 12 years, but the physical distinctions between the youthful, energetic Democrat and the dour, white-haired Republican could hardly have been more striking.
Going into that contest in Cleveland, Edwards -- a charismatic former trial lawyer -- was widely expected to outshine the incumbent with a history of heart problems and a reputation for being proudly cantankerous.
Instead, Cheney more than held his own in a seated format that suited him well. He was able to draw attention to Edwards' status as a relative newcomer on the national political scene via a rehearsed line intended to highlight his opponent's poor Senate attendance record.
"The first time I ever met you was when you walked on the stage tonight," Cheney said to Edwards in one of the debate's most memorable moments.
The assertion was later shown to be technically untrue, but during a debate in which the war in Iraq and other national security-related policies were central topics, it helped reinforce perceptions of Cheney as an experienced Washington hand, while Edwards was untested.
In what was indisputably a "change" election four years later, Sarah Palin sought to turn her relative youth into an advantage. At an Ohio rally three days before she squared off against Biden, the 44-year-old Palin drew attention to her Democratic opponent's senior status.
"I've never met him before," she said of Biden. "But I've been hearing about his Senate speeches since I was in like second grade."
Going into their face-off in St. Louis, Palin benefited from coming into the debate with the lowest expectations of any vice-presidential candidate in memory.
Her performance, in which she winked for the cameras and avoided answering many of moderator Gwen Ifill's questions directly, was largely deemed a success in light of her ability to stand toe to toe against a Washington fixture who had spent decades steeped in the intricacies of domestic and international policy.
Biden is now four years older, of course, and in Danville, Ky., on Thursday night he will be matched against an opponent two years younger than Palin was in 2008.
To put that age disparity into starker perspective, when Biden was first sworn into the U.S. Senate in 1973, Ryan was not yet 3 years old.
According to Obama campaign officials, the generational gap between the two candidates has not specifically been factored into the preparation Biden has been undertaking since Sunday in Wilmington, Del.
Maryland Rep. Chris Van Hollen has been playing the role of Ryan in hours-long mock debate sessions, which have been fueled by caffeinated drinks, Gatorade, and animal crackers. At 53, Van Hollen is more than a decade Ryan's senior but has been in Washington four years less than the GOP vice-presidential nominee.
Belying his relative youth, Ryan has spent almost 14 years as a congressman and has served as the ranking Republican on one of the most prominent bodies -- the House Budget Committee -- for almost six years.
According to Republican strategist Tucker Eskew, who was part of the team that helped prepare Palin for her debate against Biden, any effort to inject the age gap into Ryan's thinking could backfire.
"The last thing you want him thinking about is, 'I'm going into the arena with a man with 30 years more experience'; you want him thinking he's got the right ideas," Eskew said. "He's taken it to President Obama in face-to-face settings, so I don't think he'll be intimidated. I would be well-briefed on some of [Biden's] pre-administration record because it's ripe. I wouldn't want to over-pluck those fruits, but I would want to have a few stored up and [be] ready to toss them."
But even with his years of high-level Washington experience, the fact remains that Ryan is a year younger than Biden's eldest son, Beau, and he often projects an even younger figure on stage.
The sensitivity involved with preparing their Generation X candidate to square off against a man who will soon enter his seventies is something the Ryan camp says it has addressed explicitly. That was done with the help of former Solicitor General Ted Olson, Ryan's mock debate opponent, who is close to Biden's age.
"It's obviously something we're aware of," said a senior Ryan campaign aide. "I think Ryan would tell you that he's frequently been the youngest guy at the debate on Capitol Hill. He's used to debating people who are his senior and doing it in a respectful but effective way."
The Romney campaign hopes that the challenger's youth will appeal on a visceral level to younger voters just tuning into the campaign more seriously, who may like President Obama but are open to a candidate more relatable to them personally than the man at the top of the GOP ticket.
But despite Biden's relatively advanced years, both sides acknowledge that his energetic, happy-go-lucky -- and, yes, gaffe-prone -- persona (which has been parodied to great effect over the years by The Onion) may have a certain appeal to a younger demographic.
"The vice president is a very charming man, and you always have to kind of think about that charm and the potential for an 'Irish uncle' moment," a Romney campaign aide said.