For months, Chris Christie has struggled to grab national headlines. He toiled away in Iowa and New Hampshire without any real move in the polls. As his aides grumbled in frustration, Christie told them he valued the paced campaign, where behind-the-scenes work made the difference. After all, it’s how he built—and won—cases as the U.S. Attorney for New Jersey: have your homework in hand and be ready to take advantage of the opponents’ errors. And they always made a mistake.

The groundwork has the potential to pay off. The terror attacks in Paris, which left at least 130 dead, have shifted the race for the Republican Party’s presidential nomination toward national security issues. It’s a move Christie is ready to use to his advantage. “Terrorism is not theoretical. It’s not something I discuss in the basement of the Capitol, in a subcommittee meeting,” Christie told Florida activists in mid-November. Terrorism in Christie’s world is personal.

Years before Christie became Governor, terrorism was a major part of his job. As the U.S. Attorney for New Jersey, he lead major national security prosecutions after the September 11, 2001, terrorism attacks, and the lesson of his almost seven years in that office still shapes him today. “Who among us has truly been tested?” he asked the activists, casting himself as the lone Republican contender who can combat America’s enemies. It’s a theme he will hammer when he speaks to the Council on Foreign Relations on Tuesday in Washington.

Christie’s record as U.S. attorney, which has been glossed over as he has struggled in his presidential campaign, also reveals lesser-known qualities of a politician who has branded himself a tough-talker who never backs down from a fight. As a prosecutor, in repeated cases against corporate wrongdoers, Christie displayed a different set of attributes, including a willingness to compromise and settle cases with targets of his investigations. He broke repeatedly from the reckless bull-in-a-china-shop reputation Christie’s critics like to ascribe him. Instead, in conversations with Christie, it’s clear he is more analytical and prepared than he likes to let on.

Two events in 2001 shaped his approach to how he wielded power: the terrorist attacks of Sept. 11, and a corruption case against accounting giant Arthur Andersen.

The former is now front and center in the Christie campaign, but the latter has also been there from the beginning. The question is whether the tide will shift enough in the Republican Party to let him rise to victory. ” I’m the only person in this race who has actually done this before,” Christie said on CNN on Nov. 23. ” National security is not an option. It’s a fundamental right. And that’s what we will be focused on.”

LAWYERS IN THE Bush White House phoned Christie on Sept. 10, 2001, to let him know that the 39-year-old was their pick to be the Justice Department’s proxy in New Jersey. The next day, the scope of that role changed as the United States faced its deadliest day at home since the Civil War.

“I went to the funerals. I saw the carnage,” Christie says of the attacks of Sept. 11, 2001. For hours that day, he could not get in touch with his wife, Mary Pat, who was working on Wall Street at the time. He had brief contact with her after the first plane struck the World Trade Center but spent hours trying to get through to her afterward. Christie still gets emotional when talking about his college sweetheart and that day when he feared he would soon be raising his four children as a single dad. When she finally returned to New Jersey, caked in dust from Lower Manhattan, Christie knew his new job would be anything but normal. The world had changed.

On a smaller scale, that day also reshaped how Christie would structure the office he would start leading in January 2002. His Terrorism Unit was given the same stature as the Violent Crime Unit and the Narcotics Unit—a huge promotion of a previously backwater operation. Christie met with his dedicated terrorism investigators frequently and reported developments to the Deputy Attorney General for the United States. That man, James Comey, is now the FBI Director and someone Christie speaks of fondly.

Christie’s new structure chaffed many of the 125 longtime prosecutors who previously moved freely between silos and were already predisposed to distrust the newcomer and his full embrace of new surveillance programs. “That was the first place where I ran things,” he says.

Christie recognized his new employees had reason to be skeptical of this political-animal-turned presidential appointee. “I had never prosecuted a case before,” Christie acknowledges. “A lot of these folks were brilliant lawyers.” But Christie worked to quiet many of his critics.

Some still grumble. In their telling, Christie rushed to talk to the press about headline-grabbing cases in an effort to boost his political fortunes. Others are more forgiving. One prosecutor who lost a case remembers being called into Christie’s office after the loss. “You know what it says on this building? We’re the Department of Justice, not the Department of Prosecutions,” the former assistant U.S. attorney recalls. “Justice means that some days, we lose.”

Christie’s favorite prosecution to cite is what is now known as the Fort Dix Case. In May 2007, the FBI and U.S. Attorney’s Office announced they had arrested five men for an alleged plot to kill American service members, including at New Jersey’s Fort Dix Army base. A sixth man was arrested on charges he provide the guns for training. The case took 16 months to build. Four men received life sentences and a fifth was sentenced to 33 years in prison. The sixth suspect pleaded guilty on firearms charges and was given 20 months in prison.

In a separate case, Christie’s office prosecuted 70-year-old British national Hemant Lakhani on charges he offered to broker the sale of shoulder-fired missiles to shoot down American passenger planes. Lakhani was sentenced to 47 years in prison. He died in 2013.

Then-U.S. Attorney Chris Christie heads to a news conference following the indictment of N.J. Senator Joseph Coniglio in Newark, N.J. on Feb. 14, 2008. William Perlman—The Star-Ledger/Corbis

U.S. officials at the time praised the Patriot Act as a tool to foil both attacks. “The Lakhani investigation would not have been possible had American, Russian and other foreign intelligence and law enforcement agencies not been able to coordinate and communicate the intelligence they had gained from various investigative tools,” then-Attorney General John Ashcroft said during a 2003 speech in Boise, Idaho. “The Patriot Act has truly allowed us to build an extensive team that shares information and fights terrorism together.”

During the GOP’s first debate, Christie used that experience to criticize Sen. Rand Paul and his opposition to the surveillance provisions of the Patriot Act: “I’m the only person on this stage who’s actually filed applications under the Patriot Act, who has gone before the Foreign Intelligence Service court, who has prosecuted and investigated and jailed terrorists in this country after Sept. 11.” It won Christie applause, yet his poll numbers didn’t improve.

THE ARTHUR ANDERSEN case, meanwhile, is an example of the exact type of case Christie didn’t want to bring. Then one of the Big Five accounting firms, Arthur Andersen counted Enron as a client when the energy firm collapsed. Federal investigators wanted to know how the auditing firm had missed signs, whether the errors were intentional, or if accountants looked the other way to keep a high-paying client happy. Instead, Arthur Andersen executives were less than helpful and documents were destroyed.

The company itself—not its employees who might have been responsible—was indicted and found guilty. The trial put the company out of business. The conviction was overturned on appeal, but not before the company’s reputation was destroyed and its employees forever branded with a Scarlet Letter, representing Andersen, not Adultery.

Christie had watched wall-to-wall coverage of the case, and it made him uncomfortable. He decided he did not want to run his office in that way. Instead of bulldozing New Jersey companies facing smaller-scale fraud cases and leaving their employees out of work, Christie preferred to build a case against the firms and then bring their leaders in for a take-it-or-leave-it chat. Ultimately, seven New Jersey corporations accepted deferred prosecution agreements, or deals with the government that let them avoid trial in exchange for the companies hiring independent monitors to oversee operations and put in place guards against future wrongdoing.

Christie often was relieved they were open to the deals. “Put the company itself out of business? Lose all the jobs?” Christie asked when asked about the alternatives. He pointed to a corruption case he built against St. Barnabas Health Care System, the state’s largest, for double- and over-billing Medicare and Medicaid services. St. Barnabas paid $265 million to settle the case. “What are you going to do?” Christie asks. “Close the hospital, the largest hospital that serves the poor?”

In the case of one medical device manufacturers, Christie’s conversation started rather contentiously. “I’m not agreeing to this because you’ll never really bring this case against us,” one company’s CEO told Christie. The prosecutor knew his team has years of interviews with doctors, salesmen and informants. Documents were irrefutable. “It’s been nice talking to you,” Christie remembers replying, before promising an indictment within the month. A two-and-a-half year investigation had just ended with the thud of a receiver. One of Christie’s top aides put his head between his knees and whispered, to himself: “Oh, God.”

Christie knew his investigation had plenty to win an indictment and likely a conviction. “He knew it,” Christie said of the CEO on the other end of that call. “He was testing me. … He called back an hour and a half later and tried to pass it off on his board.” The company joined four others as part of a $311 million settlement that allowed them to avoid prosecution on allegations they were paying kickbacks to doctors who used their technology.

But such deals came with skepticism and strings. In a separate case, Christie negotiated a deferred prosecution agreement with Bristol-Myers Squibb, a drug-maker accused of defrauding its investors. Mary Jo White, now the chairwoman of the Securities and Exchange Commission, represented Bristol-Myers Squibb in the negotiations.

Christie’s investigators discovered Bristol-Myers Squibb was having pharmacies buy surplus inventory they didn’t need in order to pad profit reports and meet earnings forecasts. As a result, the company’s value grew even though the earnings were bogus. Christie and White in 2005 reached a $300 million settlement payment to defrauded investors and $540 million to settle shareholder lawsuits. The company also accepted an in-house federal monitor—a position that would dog Christie during his first run for Governor.

As part of its penance, the company also proposed paying for a professor of business ethics at a law school. The company initially offered to pick up the tab at a school in New York. No way, Christie said. “This is a New Jersey case. Pick a New Jersey school,” Christie replied. Rutgers already had such a program, and there was only one other law school in New Jersey. It just happened to be Christie’s alma mater, Seton Hall. “It couldn’t have mattered less to me,” Christie says. “I didn’t get anything out of it. I was long graduated from Seton Hall.” (The Justice Department signed off on the agreement, but would later limit U.S. Attorneys’ ability to negotiate such deals.)

Christie’s critics pounced on the $5 million payment to Seton Hall, and to this day are trying to use it as a way to suggest he is another pay-to-play New Jersey politician. Christie to this day says he has no regrets about the deferred prosecution agreements, including the professor position. To him, it matters less about whether there was a conviction than whether the illegal behavior ended. “The goal as the U.S. Attorney is to stop the conduct,” Christie says. “If you’ve stopped the conduct, you’ve won.”

NOT EVERYONE AGREED. Congressional Democrats probed the practices of the George W. Bush Justice Department, continuing even after he left office in early 2009. As part of one hearing, Democrats summoned Christie to testify about the deferred prosecution agreements and who got rich from them. Were these, they asked, no-bid kickbacks for political allies? Their questions were not without merit.

For instance, Christie hired former Attorney General John Ashcroft, his one-time boss, to monitor Zimmer Inc., one of the firms that settled with the government. In turn, Ashcroft’s company charged between $1.5 million and $2.9 million a month to monitor the medical device company. By the time Christie arrived in Washington to answer lawmakers’ questions, The Ashcroft Group had earned $52 million on that case. “To me, that is outrageous,” Rep. Steve Cohen chided Christie. “I don’t care what you did. It is not worth $52 million,” the Tennessee Democrat continued. “Even if you took steroids and hit 70 home runs, it is not worth $52 million.”

Lawmakers also wanted to know why he named David Kelley to a post to oversee the Bristol-Myers Squibb settlement. Kelley two years earlier, as a former prosecutor, declined to bring securities fraud charges against Todd Christie, the future-Governor’s brother. Was this payback for sparing a Christie Family?

The hearing turned “testy,” “charged with political tension” and “politically charged bedlam,” in the words of the day’s news coverage.

That is putting it mildly, Christie chuckles. In his view, Democrats had hauled him to Washington to grill him—and to script television ads that they could use against him during his run for Governor. Christie was pushing his time as prosecutor hard, and it was breaking through. He had convicted more than 135 New Jersey public officials for corruption; none he indicted was acquitted. In all, he snagged 310 corruption convictions, the most of any U.S. Attorney during the period he was in office.

Christie suggested that Washington Democrats were merely looking to use the hearing goad Christie into an eruption that they could use to help New Jersey Gov. Jon Corzine’s reelection. “They hadn’t completed the Corzine TV commercial in two-and-a-half hours,” Christie says.

Christie’s lawyers had negotiated his appearance and told the committee that he had a train to catch at 2 p.m. Whether they were done or not, Christie had plans to board the train heading north. When that hour neared, Democrats protested. Christie was having none of it. “I don’t want to cut anybody off, but I need to go and catch a train, sir,” Christie said.

These days, Christie finds the incident amusing. “I had a 2 o’clock train. Adios,” he says, laughing that he gave himself plenty of time to walk to his platform. “Listen, with the time that I left myself, I could have crawled to Union Station. I wasn’t going to miss that train.”

Back home in New Jersey, Democrats hit Christie for his exit but it wasn’t enough to derail him. It was fall of 2009, and the sheen of Barack Obama was wearing off. Corzine campaigned with Obama during the last weekend before Election Day. “He’s one of the best partners I have in the White House,’’ Obama said. “We work together. We know our work is far from over.’’ More than 5,500 people joined a joint Obama-Corzine rally in Camden, and another 11,000 turned out later in Newark.

Yet Christie prevailed, and the White House quickly realized that the 2008 campaign and Obama’s ability to help fellow Democrats was clearly in in the past. In the West Wing, aides nervously looked ahead to the 2010 midterms, when Democrats would be routed in what Obama himself called a “shellacking.” And Chris Christie became an instant star, a rising voice in the GOP, a law-and-order prosecutor who won in deep-blue New Jersey.

Some of his advisers urged him to consider a 2012 bid for the White House. He passed on that campaign, even after former First Lady Barbara Bush phoned the Christies urging them to run. “She was putting the spotlight on the sunny side of the street,” Christie says of the conversations between Mrs. Bush and Mrs. Christie. Christie backed the eventual nominee, former Massachusetts Gov. Mitt Romney, and Mrs. Bush is now backing the also-struggling campaign of her son, former Florida Gov. Jeb Bush.

CHRISTIE’S WHITE HOUSE run in 2016, indeed, is finding less measurable success than his time as U.S. Attorney. He is struggling in the polls, has yet to have a moment that catapults him to the top of the heap and is finding fewer headlines than Donald Trump. Undeterred, Christie has continued campaigning, especially in New Hampshire, where he sat down with TIME for an interview in Manchester.

“I can’t worry about anyone else. I have enough to worry about on my own,” Christie says.

Christie is keeping his head down and doing the person-to-person campaigning that he hopes is enough to undo the stench of investigations that continue back home. Indeed, the current U.S. Attorney for New Jersey is looking into a bridge closing scheme that appears to be political payback orchestrated by Christie’s gubernatorial aides and allies. No evidence suggests Christie knew of, or ordered, the closing of ramps onto the George Washington Bridge. “That certainly didn’t help,” Christie says.

It comes up in every interview—during the one with TIME, he brings it up first. “It’s one of the elephants in the room,” he says with a shrug. He has his answer ready, of course. He’s been running for months and it’s easy to blame three allies who have been indicted.

“For me, I have to keep running the race I want to run,” Christie goes on. He knows he has a reputation as a bully and tough-talking politico full of bravado. But as he spends time—two hours or more at some events, taking every question any voter posits him—he is hoping voters come to see him as a pragmatic figure. And if that doesn’t work, Christie knows a thing or two about building an airtight case against his foes and going on the attack. With Iowa little more than two months away, Christie might want to start reviewing the evidence.

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Write to Philip Elliott at philip.elliott@time.com.