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Ronald Reagan, the United States' oldest president while in office, once quipped, "Thomas Jefferson once said, 'We should never judge a president by his age, only by his works.' And ever since he told me that, I stopped worrying."

That's exactly what political analysts suggest for the candidates in the 2008 presidential election. Quit worrying. Birthdays matter less to voters than vitality and seasoning.

"You can be a very youthful 75, be charismatic, and fill the room. Or you can be an old-looking 60 and convey the image of being tired and over the hill," said Mike Franc, vice president of government relations at the conservative D.C.-based think tank the Heritage Foundation.

As for the possible taint of being too young for the Oval Office, Franc said, "It all depends if the youthfulness projects any inexperience."

The impact of age on a candidate's chances dates back to the political debate between Sen. John F. Kennedy and Vice President Richard Nixon in September 1960. Visual cues advantageous to Kennedy and the stark differences between each man's delivery and confidence in front of the camera reinforced an image of Kennedy as the young man of the future while Nixon seemed the old man of the past. Kennedy was 43, Nixon was 47.

"Nixon just looked older," said Jeff Berkowitz, Chicago-based political reporter and host of the local "Public Affairs" cable talk show. "JFK had that youthful look."

Twenty-four years later, President Ronald Reagan, 73, was quite aware of his advancing age as he campaigned for a second term in office. For him, said communications strategist Eric Dezenhall, projecting a youthful image over his age was important.

"We dealt with it everyday," said Dezenhall, who worked in the press office in the Reagan White House and recalled an edict that Reagan never be photographed "around cemeteries or death images."

When the age difference between Reagan and Democrat Walter Mondale, 56, became an issue in the 1984 campaign, Reagan skillfully diffused it when he said to the panelists during the second presidential debate in October, "I will not make age an issue of this campaign. I am not going to exploit for political purposes my opponent's youth and inexperience."

The witty crack caused even Mondale to smile alongside the audience's laughter. Reagan won in a landslide a month later.

"This guy did not come across as a man in his 70s — he came across as a linebacker, he lumbered when he walked," Dezenhall said. "I think appearance does play a role."

Whether Republican presidential candidate Sen. John McCain, 70, can project the same virility has been a question so far in the current campaign. Eight years after his first unsuccessful bid for president, analysts say McCain, who if elected would become the oldest first-term president at age 72, must ensure that his age and his past bouts with skin cancer don't create an image of fragility or weakness.

"I don't think the fact that he's eight years older than when he ran for president last time is a killer for the campaign, but I think in some people's minds he might be nearing a tipping point," said Mark Wrighton, political professor at the University of New Hampshire.

When asked about his age during an interview last month with "FOX News Sunday," McCain dismissed concerns that "he's just too old."

"Watch the campaign. Watch my energy level. Watch how I articulate," he said. "I have the experience. I've been in war. I know both war and peace. I know the face of evil. I'm ready to serve."

"I would challenge anybody to keep up with him. I mean, he is 70 going on 40. I'm not kidding. He hiked the Grand Canyon rim to rim with our son this summer. Age is not a factor here," added his wife, Cindy.

McCain's age does provide him with some experiences other White House hopefuls don't have. Unlike any of the top-tier candidates, not only did McCain serve in Vietnam, he was a prisoner of war. His experience in Congress spans nearly 25 years.

"If I'm John McCain's campaign I am thinking about two things — putting him in situations that project energy and two, taking advantage and capitalizing on that vast experience he has," said Berkowitz.

Baby Faces and 'Hunkitude'

While McCain might be defending his advanced age, Illinois Democratic Sen. Barack Obama, the youngest candidate in the race at age 45, has been targeted for his apparent youth and inexperience.

"I ultimately think a lot of people think he's way too young," said Dezenhall.

"My guess if you were comparing McCain and Obama, age is probably more of an issue for Obama. That's his challenge," said Wrighton.

"It all depends if the 'youthfulness' projects inexperience," said Franc. "If you are captivating people with a new idea or connecting on an emotional level, even if you are 40, I don’t think that voters will hold that against him."

Fellow top-tier Democrat and former Sen. John Edwards may be eight years older at 53 and four years older than his debut in presidential politics in the 2004 election, but he is still battling the "baby face" label and possibly even worse, the "prettiness" curse.

"I think his issue is not so much his age, but another shallow issue, which is the prettiness factor," said Denzenhall. "I think a lot of what John Edwards has traded on is his looks," he added, calling the X-factor "hunkitude."

Not helping Edwards is the widely-circulated YouTube.com video clip showing the former trial lawyer and vice presidential candidate, primping in front of the mirror before an interview, or reports he paid $400 for his haircuts.

But his looks and age don’t hurt either. "It's nice to have a more youthful appearance," said Berkowitz, noting the perfect candidate might espouse both vigor and knowledge.

"If you could project the experience of John McCain with more youthfulness and energy, you're better off," Berkowitz added.

When the Time is Right

Regardless of the age differential in the presidential race, timing and mood are everything, said Bruce Gronbeck, politics professor at the University of Iowa.

When Reagan beat President Jimmy Carter in 1980 it was after the country hit one of its lowest points in the century, Gronbeck said, and voters were ready for the older and more politically seasoned Republican.

"When Reagan rolls in, the country is in double-digit inflation, the Iran crisis and a crisis of government" are plaguing the Carter administration, he said. "After the Carter legacy, the country was very much ready for wisdom and age."

The election of Kennedy in 1960, Gronbeck said, marked an era of "of optimism and strength and vision," after eight years under President Dwight D. Eisenhower, who was 70 years old when he left office.

And while it may not have been the only factor, analysts point out that former President Bill Clinton, whose wife, Sen. Hillary Clinton, 59, is now running for president, struck a chord with the younger baby boom generation when he beat President George H.W. Bush in 1992. Clinton was 46; Bush was 68.

What the electorate is looking for today has "yet to be defined," said Gronbeck, but a real sense of insecurity — economic or otherwise — plus the unpopular war in Iraq has set the stage for the next candidate to step in and use his or her age for benefit.

"Both younger and older candidates can turn it to their advantage."