Jon Huntsman’s expected endorsement Monday morning of Mitt Romney comes as something of an unexpected coda to years of rivalry between the two GOP powerhouses and White House hopefuls.

Former Utah governor Jon Huntsman (R). (Alex Wong/Getty Images)

There have been their face-offs at recent debates, including one especially contentious moment earlier this month when Huntsman blasted Romney — in Mandarin — over his stance on China’s currency policy.

But one of the most heated confrontations between the two came not in the current GOP race but in the late 1990s, when both Huntsman and Romney were in the running to lead the 2002 Salt Lake City Olympics.

In early 1999, Salt Lake Organizing Committee Chairman Robert Garff, who had known Romney since the two were children, submitted Romney’s name to then-Gov. Michael Leavitt (R).

Michael Kranish and Scott Helman, two veteran Boston Globe reporters who have authored a new book on Romney due out on Tuesday, tell the tale of what happened from there.(The Post obtained an advance copy of the book.)

From “The Real Romney”:

The only other serious candidates—Jon Huntsman, Jr., one of Utah’s most prominent and politically connected figures as the son of the billionaire industrialist Jon Huntsman; and Dave Checketts, the chief executive of Madison Square Garden—were also Mormons with Utah roots. But Garff wanted Romney. So did Leavitt. “I was looking for a businessman who had a good political instinct,” Leavitt said.

The younger Huntsman, then a top executive of his father’s chemical conglomerate and a former U.S. ambassador to Singapore, grew disillusioned with the search process in its final days. With Romney emerging as the likely winner, Huntsman responded by withdrawing his name from consideration, then rebuffing an invitation to serve on Romney’s management committee. “A search was never fully carried out,” Huntsman complained. “If I was not able to support the process which they were employing in bringing in new leadership, I shouldn’t be serving in a position like that.”

Romney’s tenure as the head of the Salt Lake City Olympics, of course, went on to become a pivotal part of his narrative as a leader skilled at turning even the direst crisis into a success.

At the time, there were also tensions between the senior Huntsman and Romney over how involved the Church of Latter Day Saints should be in the 2002 Olympics, Helman and Kranish write:

Romney’s initial decisions exacerbated concerns about the level of church participation. He had requested an additional $8 million — on top of the $5 million it had already committed — in lent property and cash from the church, among other contributions, as he tried to strengthen the Games’ financial position. And he hired Fraser Bullock, another prominent Mormon who had been a partner at Bain, as his chief operating officer.

The moves prompted the elder Huntsman to assail Garff and Romney for exploiting their ties to the Church of Jesus Christ of Latter-day Saints. “We’ve got a chairman who is active LDS, now we’ve got a present CEO who is active LDS,” Huntsman said. “They claim they’re going out [to] really scour the world to find the best person, so Mitt brings in one of his cronies to be the COO. Another broken promise. Because we’ve got three LDS folks who are all cronies. Cronyism at its peak. ... These are not the Mormon Games.”

Ultimately, Garff, Leavitt and Romney met with the elder Huntsman and smoothed out their differences, the authors write.

Romney and Huntsman also clashed in the lead-up to the 2008 race. The Post’s Jason Horowitz chronicles the events surrounding Huntsman’s endorsement of Sen. John McCain (R-Ariz.) in July 2006 — an announcement that came despite a series of moves that suggested Huntsman was headed toward an endorsement of Romney:

Early in the campaign cycle, Salt Lake City’s Deseret News described Huntsman as “backing” Romney, after the then-Utah governor told the paper’s editorial board that he was writing position papers for Romney on China. Huntsman and his wife, Mary Kaye, met privately with Romney and his wife, Ann, according to a Romney adviser, who added that Huntsman on multiple occasions pledged his support to Romney and was privy to campaign strategy. Then, in July 2006, Romney read in the newspapers that Huntsman Jr. had endorsed McCain for president.

Not surprisingly, Romney was livid.

“There were some angry calls,” said Karen Huntsman (Jon Huntsman’s mother). Speaking as serenely as ever, she adjusted the cuff of her sleeve and said: “If I had a son running for president, and my best friend voted for his opposition, it wouldn’t make me mad. That’s your choice.”

All of which will make watching Huntsman’s expected endorsement of Romney on Monday all the more intriguing.