Clinton met Spence while working on George McGovern's failed 1972 presidential bid, counting Spence as among "the best friends I've ever had," on page 58 of her 2003 autobiography, "Living History."
"We would sit outside at the end of 18- or 20-hour days, trying to figure out what else we could do in the face of ever-worsening poll numbers," Clinton wrote.
Fast forward more than three decades later, and Clinton is the one running for president, facing a formidable opponent touting an inspirational message.
Spence has been tapped to help.
He is known in advertising circles as the "Idea Man," even renaming his Austin-based ad firm "GSD&M's Idea City." The firm is owned by media giant Omnicom.
Spence's clients have included Southwest Airlines, Wal-Mart, and BMW, and he's done pro bono work for Bill Clinton's Global Initiative.
"He's a great pitchman, a big concept guy," said Dowd. "He can really create enthusiasm, a sense of purpose."
Spence declined to be interviewed for this story. But his company boasts an endorsement from the former president on its Web site: "Thanks for the creative solutions you bring to life, not just for your clients, but for our country and the world," reads a quote from Bill Clinton.
In October, the ad firm Spence founded 36 years ago hit a rough patch, laying off almost 120 people, after losing AT&T, one of their biggest clients.
The layoffs coincided with Spence's first installment of his spiritual trek across America. Spence walked from New Hampshire to Pennsylvania, logging about 20 miles a day, for 10-hour stretches, hoping to become a "better marketer and a better person."
The Clinton campaign may be more interested in whether the trek worked on his marketing skills.
Spence is one of several new faces getting a bigger role as Clinton gears up for key primaries in Nevada, Michigan, South Carolina and the big Super Tuesday primary states on Feb. 5.
Before the polls closed, Tuesday, the Clinton campaign tapped Maggie Williams, Clinton's former chief of staff from her days as first lady, to take the reins of the campaign, and will be in charge of day-to-day operations.
"Maggie brings a comfort level," a Clinton campaign source told ABC News. "She is a woman. She's a minority. She can talk the talk, and she understands the field operations."
Disappointed in their stunning third place loss in Iowa, and euphoric over their narrow New Hampshire victory, the expanded roles for trusted advisors are a sign the campaign is throwing everything they've got into wooing voters for the next critical phase of the primary race.