GREENVILLE, S.C.—South Carolina is known for its blood sport politics, and this presidential cycle is living up to that reputation.

Take the events of the past 24 hours: Marco Rubio and Ted Cruz sparred over a photo-shopped image and false advertising, Donald Trump threatened to sue Cruz over a negative ad while the Texas senator offered to administer the deposition himself, and the Jeb Bush campaign struck back at rumors his operation is out of cash.

And as if this Republican campaign isn’t already stranger than fiction, Trump spent Thursday feuding with the pope himself.

It all comes amid significant ground shifts in the GOP race for the White House. Trump continues to lead the field here in polls, but Cruz and Rubio are engaging in their most heated battle yet to get ahead. Bush hoped the admiration for his family and its extensive network would help him craft a comeback narrative, but his campaign appears to be on life-support, with his own event attendees openly questioning his strategy. Trump hasn't pulled any punches with Bush, criticizing his family and accusing former President George W. Bush, who campaigned for his brother earlier this week, of lying about Iraq War intelligence.

Saturday’s primary is expected to winnow the field in a way New Hampshire could not. But each of the candidates left isn’t ready for a plane ticket home. Thus, the Palmetto State has become a battleground and a bloody one at that.

“When you come to South Carolina, it’s a blood sport. Politics is a blood sport,” Gov. Nikki Haley said at a press conference Thursday in Anderson. “I wear heels; it’s not for a fashion statement. It’s because you’ve got to be prepared to kick at anytime.”

Haley helped change the trajectory of the race Wednesday evening by endorsing Rubio.

Candidates coveted the backing of the young, popular Indian-American governor, and it could move support toward the Florida senator and away from Bush or John Kasich. She spent Thursday campaigning around the state for Rubio, and plans to do so again on Friday.

The Rubio campaign spent Thursday morning pushing back against a website the Cruz team assembled that used a photo-shopped picture that portrayed him shaking hands with President Obama. The website hits Rubio for supporting fast-track trade authority in the Senate and accuses him of undermining immigration laws.

“I think this is now a disturbing pattern, guys,” Rubio told reporters before an event at a hotel in Anderson. “Every day they are making things up.” Rubio said it was “startling” to see Cruz attack him for supporting Trade Promotion Authority, when Cruz co-authored an editorial with now-Speaker Paul Ryan in the Wall Street Journal supporting it as a way to give lawmakers more say in future trade agreements.

The race between Rubio and Cruz has grown especially heated the past several days as both are hoping to beat the other here to gain momentum. The RealClearPolitics polling average shows the two neck and neck for second place.

Boosted by a win in Iowa, Cruz is aiming for a strong finish in South Carolina to cast him as the conservative choice and propel him into states in the deep South that hold primaries on March 1. Here and elsewhere, Cruz is casting himself as the only true conservative in the race, and Rubio as someone who bends in the Washington wind.

After a poor showing in New Hampshire and falling behind Cruz after a rough debate performance, Rubio is looking for redemption in Saturday’s primary. He is campaigning around the state with Haley, Sen. Tim Scott, and Rep. Trey Gowdy, casting his group as the new face of the conservative movement that can consolidate the GOP and win the general election. He has sought to undermine Cruz on national security issues, which play an outsized role in this military state.

The Rubio campaign also sees an opening for the group in the feud between Cruz and Trump. On Wednesday, Trump sent Cruz a cease-and-desist letter, threatening to sue over an ad hitting the billionaire businessman over abortion rights. In response, Cruz held a press conference where he offered to take the deposition himself, calling the suit frivolous, and appearing gleeful at the idea of getting Trump under oath. Rubio senior strategist Todd Harris said the situation made Cruz appear “both unhinged and unpresidential.”

Trump continued his attacks on Cruz at an evening rally in Gaffney, the South Carolina town made famous by Netflix’ “House of Cards.” “I agree with Rubio. The guy lies. He’s a liar,” Trump said. “And I know the difference between having fun and playing the games, you know -- we’re in politics.”

Thursday morning, though, Trump had a different target: his holiness. Pope Francis weighed in on the GOP race by saying, “A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian.”

During a rally on Kiawah Island, Trump said that “if and when” ISIS takes the Vatican, “the ultimate trophy,” the pope "would have only wished and prayed that Donald Trump would have been president.”

In a statement, Trump called the pope’s remarks “disgraceful.”

“No leader, especially a religious leader, should have the right to question another man’s religion or faith,” he said. “They are using the pope as a pawn and they should be ashamed of themselves for doing so, especially when so many lives are involved and when illegal immigration is so rampant.”

The issue quickly made the rounds on the campaign trail. Rubio, a Roman Catholic, said the United States was the most “compassionate” nation, but that “this country has not just a right, but an obligation to control the process by which people enter the United States,” just as the Vatican controls its own border.

It was a bizarre day on the campaign trail, indeed. But South Carolina is no stranger to this sort of thing.

This year voters have complained of push polls in which voters assume they are taking an ordinary phone survey before being bombarded with reasons not to vote for a particular candidate. This kind of dirty politicking has become so commonplace in South Carolina that the Charleston Post and Courier has a form for voters to fill out to keep track of rumors, fliers and phone calls.

Rick Santorum accused Mitt Romney in the 2012 South Carolina primary of dirty politics, referring to automated calls playing audio of Santorum endorsing Romney during his 2008 bid for president. John McCain took a blow in the 2000 South Carolina primary when rumors circulated that his adopted Bangladeshi daughter was his illegitimate black child.

His campaign also battled whispers that his wife was a drug abuser as well as anonymous calls slamming his candidacy.

“South Carolinians are used to this,” Haley said. “And they can cut through all the mud.”

Ellie Potter contributed to this story.