In any other election year, the decision by a failed presidential candidate to back his party's front-runner would seem inevitable, nothing more than a blip in the news cycle.
For starters, it produced one of the campaign's most indelible viral images — the typically blustery Christie standing silently behind his former rival, whom he called "Mr. Trump," following the New York businessman's Super Tuesday victories.
It also triggered a backlash against the governor and marked a turning point for a political party struggling to decide whether to embrace or fight the man who has the best chance of becoming its nominee.
Some of Christie's supporters swiftly turned their backs on him, condemning the endorsement of Trump as an abdication of political principles and evidence of rank opportunism. There was even dissension within the governor's close-knit inner circle. According to people with knowledge of the conversations, two of his longest-serving advisors, Maria Comella and Mike DuHaime, were skeptical or disagreed with his decision.
Christie, who dropped out of the presidential race after a poor showing in New Hampshire, said he endorsed the candidate with the best shot of beating Hillary Clinton, the expected Democratic nominee. He downplayed his past statements that Trump is unfit for the presidency.
"Donald Trump is the person on that stage now who is best suited, best prepared to make America the kind of leader around the world it needs to be again," he told Fox News.
The endorsement shouldn't be that surprising, Christie suggested — after all, the two men have been friends for years. Yet his decision, made a few days after Trump won the Nevada caucuses, knocked the political world on its heels.
Christie had spent years curating an image as a policy-focused administrator who reached out to Muslims and Latinos, and he was rewarded with rock star status in the national Republican Party. Now he's backing a candidate who has insulted minorities, shown a casual disregard for policy discussions and is reviled by the party's establishment.
In New Jersey political circles, the endorsement was the kind of news that's so big, people remember where they were when they heard about it.
Lawrence Bathgate, a major Republican donor in the state, was eating at a restaurant with a local mayor who suddenly said, "Christie is endorsing Trump." Bathgate dismissed the idea as ludicrous, but the mayor insisted, "No, he's doing it right now, look at the TV!"
Bathgate turned around to see the news — Christie was on stage becoming the first sitting governor to publicly back Trump.
Christie had met with Trump that morning in New York City. When he agreed to endorse the businessman, he flew to Texas for the announcement.
Missing from the trip were DuHaime and Comella, advisors who have worked with Christie since his first campaign for governor in 2009.
Republicans who have battled Trump quickly vented their anger after the endorsement.
"Like Trump, Chris Christie is a pathetic, corrupt man with a tiny ego," tweeted Tim Miller, who was a spokesman for Jeb Bush, the former Florida governor who dropped out of the presidential race after falling short in South Carolina.
Meg Whitman, the Hewlett Packard Enterprise chief executive who helped lead the Christie campaign's fundraising team, also rejected the idea of supporting Trump.
"Chris Christie's endorsement of Donald Trump is an astonishing display of political opportunism. Donald Trump is unfit to be president. He is a dishonest demagogue who plays to our worst fears," Whitman said in a statement.
She added, "For some of us, principle and country still matter."
Critics accused Christie of angling for a job like vice president or attorney general in a Trump administration.
Kevin O'Toole, a New Jersey state senator and ally of Christie, defended the governor's decision. He recalled how Christie traveled the country as chairman of the Republican Governors Assn., raising money for candidates and securing victories in battleground states.
"He gets vilified by the establishment when he did more to prop up the establishment than all of those naysayers combined," O'Toole said. "That's what I find hypocritical."
Christie was in Florida last week to introduce Trump at a news conference marking the businessman's cascading victories on Super Tuesday.
"Tonight is the beginning of Donald Trump bringing the Republican Party together for a big victory in November," Christie said, calling Trump's candidacy "a movement."
Christie spoke in a heavy voice, and when Trump took the podium, the governor stood wordlessly behind him, an appearance that commentators joked had the feel of a hostage video.
At a news conference Thursday outside his Statehouse office, Christie brushed off the idea that he was having any second thoughts.
"All these armchair psychiatrists, give me a break," Christie said. "No, I wasn't being held hostage. No, I wasn't sitting up there thinking, 'Oh, my God, what have I done.'"
He said that he hadn't talked with Trump about a job in his potential administration, and that he intended to finish his term and then work in the private sector. "That's my current intentions," he said. "I can't foresee the future."
Christie said he wouldn't be traveling with Trump as a full-time campaigner and was focused on governing the state, where he faces a laundry list of problems — a nearly bankrupt transportation trust fund, the crumbling economy in Atlantic City and an overburdened pension system.
A new poll released by Fairleigh Dickinson University showed Christie's approval rating at 30%. Several local newspapers have called on him to resign, and fellow Republicans have questioned his dedication to the state.
"Being governor is a full-time job," said Bathgate, who supported Bush in the election. "And if he's going to preserve whatever legacy he may have for doing things, he's going to have to work hard being governor of New Jersey."
With Christie's second and final term ending next year, Democrats have seized on the Trump endorsement as another reason to dig in their heels against the governor. State Senate President Stephen Sweeney justified his decision to block Christie's nominee to the state Supreme Court by saying he wouldn't "allow Donald Trump's agenda to be imposed on New Jersey."
With the Republican Party at odds over Trump, it's unclear how Christie's long-term political fortunes will be affected.
There's no shortage of people who consider him a "traitor to the cause," said Reed Galen, a Republican consultant in California. But the election has exposed a vast rift between the party establishment and the voters, he said, one that Christie couldn't ignore.
"Maybe Christie is smarter than all of us," he said.
Times staff writer Joseph Tanfani contributed to this report.