For the better part of a year, the campaigns have dug through every story written on rivals, every email ever sent from an account covered by open-records laws, every speech that they could find. Financial disclosure forms are as familiar as nieces’ birthdates, memoirs are dog-eared and stained, and a presidential hopeful can hardly speak in public without someone at a rival’s headquarters transcribing the utterance, just in case it contradicted something that had previously been said.

Now, it is potentially is set to pay off in South Carolina, a state that historically been amenable to the toughest attacks among the early-nominating states. Look for the toughest barbs yet when the remaining contenders meet on stage in Greenville for a CBS News debate. Already, the airwaves are turning vicious with attack ads.

“Nice guys don’t win South Carolina,” said one Republican strategist who is not affiliated with a campaign. “They often don’t even survive it.”

This is a state where the unfounded rumor of an out-of-wedlock child helped torpedo John McCain’s 2000 campaign, spurious attacks on Mitt Romney’s religion in 2008 left him hobbled and voters were aghast—and, of course, wanting more details—about Newt Gingrich’s suggestion to his then-wife that they have an open marriage. South Carolina toughens up the hopefuls and, to leave a viable candidate, they have to develop a thick skin.

Behind many of these revelations are armies of political aides armed with tools as simple as Google, as common as freedom-of-information requests and as dull as a desk in a local library. They’re not sexy, but they can be brutal.

Saturday night’s debate with billionaire Donald Trump, Sen. Ted Cruz of Texas, Sen. Marco Rubio of Florida, former Florida Gov. Jeb Bush, retired neurosurgeon Ben Carson and Ohio Gov. John Kasich will be the smallest yet. It also is shaping up to be the meanest.

Take, for instance, the sparring that took place during the most recent Republican debate. On stage near Manchester, N.H., Jeb Bush force fully challenged Donald Trump on his position on eminent domain last weekend.

Bush: Donald Trump did was use eminent domain to try to take the property of an elderly woman on the strip in Atlantic City. That is not public purpose, that is down right wrong. (APPLAUSE) And here’s the problem with that. The problem was, it was to tear down—it was to tear down—it was to tear down the house…

Trump: Jeb wants to be—he wants to be a tough guy tonight. I didn’t take the property.

Bush: And the net result was—you tried.

Trump: I didn’t take the property.

Bush: And you lost in the court.

Trump: The woman ultimately didn’t want to do that. I walked away.

Bush: That is not true. And the simple fact is to turn this into a limousine parking lot for his casinos is a not public use.

Within minutes, one-page summaries of Trump’s history with eminent domain were landing in reporters’ inboxes. They had the goods and wanted to make sure reporters had the information handy. It was, of course, clipped to make the worst parts stand out, but the documents—from at least three campaigns—had links to new stories that had chronicled the details. Many of those news stories originated from tips other campaigns had passed along earlier that week.

It was one of the most brutal confrontations so far, yet Trump still came out atop in New Hampshire.

(Democrats are not innocent in these dark arts. Sen. Bernie Sanders had ready his criticism of former Secretary of State when the pair met Thursday. “I’m proud to say Henry Kissinger is not my friend,” Sanders said of the Republican former diplomat. Clinton consulted with Richard Nixon’s Secretary of State during her four years in his former job.)

A decade ago, these operations were generically called “research” and the tasks were given to interns. The work was menial: find the rivals’ dates of birth, check if they had any traffic tickets back home, that sort of thing. (Journalists, too, made efforts to uncover new facts, but success varied from the Miami Herald essentially ending Gary Hart’s campaign based on an extramarital affair to the Boston Globe’s ersatz bombshell that Romney’s pooch once pooped on the family station wagon.)

But after the 2004 race, when competing operations were digging up dirty on George W. Bush and John Kerry, senior leaders inside the campaigns started recognizing the values. Bush’s decades-old DUI record sent his campaign headquarter in Austin roiling, and Kerry’s team never really figured out how to deal with questions about the Vietnam veteran’s service. Often passed anonymously, the questions fueled some of the most difficult news cycles for the candidates’ aides. “Once you’re on defense, you’re stuck there,” one Kerry veteran said.

These days, the goal is to keep the opponents on their heels and responding instead of peddling their own goods. “You cannot run a modern campaign without this silo,” said one campaign research chief who, like almost everyone involved in such opposition projects, refuses to have their names or affiliations attached. They want their bosses to appear to be above such mudslinging.

But there are an awful lot of rental cars parked outside the public library in Westerville, Ohio, these days. Inside, mobile scanners rapidly convert memos, speeches and hand-written notes into PDFs for review for colleagues back at headquarters.

Why? “Ohio is a wonderful place to visit this time of year,” one research chief said coyly. “And the [Westerville] collection of pro-Prohibition posters from the Temperance Movement is world class. The Anti-Saloon League is something we really never studied in school.”

Left unsaid: the brick building on South State Street houses Kasich’s records from his nine terms in Congress and four years in the Ohio State Senate. Kasich, who logged a second-place finish in New Hampshire, and his record as a legislator are about to get a lot of scrutiny—especially in South Carolina, where Kasich’s votes to streamline the military might find a hostile audience in the veterans-rich state.

This article originally appeared on Time.com