Marvin Nicholson has been indispensable to Sen. John Kerry, serving as the candidate's personal aide, or "body man" as the campaign calls him, since he decided to run for president in 2002.
"My business card reads: 'Marvin Nicholson, Chief of Stuff,' " he said. "I make sure he's got everything from his briefing books to peanut butter and jelly sandwiches."
The two met while Nicholson was working at a Massachusetts windsurfing gear shop. Over time, he became Kerry's golf caddie, then his driver and later his personal aide. Nicholson, 32, may be the only man on the campaign taller than the candidate.
He always has to be one step ahead of Kerry, ready with a pen when it's autograph time.
"My arsenal of pens," Nicholson said, showing his fully stocked inside pocket jacket. "I like to be prepared for every possible signature scenario. Our mainstay would have to be the Sharpie."
Blake Gottesman has served as George W. Bush's "body man" since 2000. On the trail, he's known as the "two-minute man." When Blake puts a speech on the podium, it's a sign that the president is about to arrive.
An interview with Gottesman was denied by the Bush campaign.
The personal aide is the keeper of the schedule. He tells the candidate when it's time to move on.
Tim McBride was a personal aide to the former President Bush.
"We developed over time a little schtick for breaking up meetings that were going too long," said McBride. "It often involved a raised eyebrow or a cough, but the secret weapon was to walk in and say, 'Mr. President, the Secret Service has blocked the street. The motorcade is waiting to go,' and that would usually evoke a reaction, 'We've got to go.' "
Kris Engskov was President Clinton's "body man" for three years.
"The way I describe it to people was: no life, no dates, no sleep and no money," he said. "They trust you; they expect you to be there for them at all times. At the end of the day, you're the only person who may not have an agenda other than to take care of them. Toward the end of our time, I feel like we were like an old married couple. We could go though an entire day and not say two words to each other and anticipate every other move."
It is the psychological support that may be most important.
"At the end of the night, we'll be in the room, we'll maybe rent a movie, have a burger and have a beer," said Nicholson. "The way that the schedule is now, [Kerry's] day is so jam-packed with event after event after press, that it's time for him to forget about all that stuff, and we just hang out."
Virtually every president has had a similar relationship with an aide.
When George Washington died, Tobias Leer was still at his side. President Lincoln had two aides, and they later became his biographers.
Before the great adventurers Lewis and Clark, there was Lewis and Jefferson. Meriwether Lewis was Thomas Jefferson's aide when he was 27. In return, he got free room and board from the Jefferson family and earned $500 a year.
Dave Powers was John F. Kennedy's legendary right-hand man.
"He used to like to be in the sack by 11:00," said Powers. "He'd hate to have you leave him right up until the time he had said his prayers and spread out. And he'd say 'goodnight, pal. Will you please put out the light?' President Kennedy was the best man I ever met and the best friend I ever had."
But many wonder: What's in the bag all the aides carry?
"Everybody always wondered what was in the bag of tricks," said Engskov. "In ours was a deck of cards. Always carried a Bible, always carried a thesaurus, there were a lot of little reference things."
Said McBride: "Souvenirs, autographs that the president may have signed during the day, an emergency bottle hairspray in case the 'do got into real trouble.
And for Nicholson, Kerry's current Chief of Stuff -- a sewing kit, a phone charger and phone book, and always peanut and butter and jelly sandwiches.
"On average we have three to four PB&Js a day," he said of Kerry. "Usually mid-morning, then again in the afternoon, late in the evening, even late at night -- PB&J."
Peter Jennings filed this report for World News Tonight.