North Charleston, South Carolina (CNN) Donald Trump on Friday cited an apocryphal story about a U.S. general who purportedly dipped bullets in pigs' blood to execute Muslim prisoners a century ago in an effort to deter Islamic terrorism.

Speaking at a rally in North Charleston, South Carolina, Trump reiterated his claim that the U.S. should "go much further" than waterboarding suspected terrorists, telling the story of Gen. John Pershing in the Philippines, who Trump said captured 50 Muslim prisoners a century ago and dipped 50 bullets in blood.

"And he lined up the 50 people and they shot 49 of those 50 people, and he said to the 50th, you go back to your people and you tell them what happened -- and in 25 years there wasn't a problem," Trump said to the audience, which grew quiet as he told the story.

Coming in contact with swine is forbidden under Islamic law.

The Trump campaign did not respond to a request for comment about what Trump was suggesting in referencing the story, which Snopes, a website that investigates urban myths and legends, was unable to corroborate a year ago.

Florida Sen. Marco Rubio called the story "bizarre" during an appearance on NBC's "Today" show Saturday morning.

"I'm sure people are offended. We hope people are offended by that. That's not what the United States is about," Rubio said.

Later Saturday, the Council on American-Islamic Relations, a leading Muslim civil rights group, said Trump's "rhetoric has crossed the line from spreading hatred to inciting violence."

"By directly stating that the only way to stop terrorism is to murder Muslims in graphic and religiously-offensive ways, he places the millions of innocent, law-abiding citizens in the American Muslim community at risk from rogue vigilantes," the group said in a statement. "He further implies that our nation should adopt a strategy of systematized violence in its engagement with the global Muslim community, a chilling message from a potential leader. We pray that no one who hears this message follows his gospel of hate."

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Muslim Advocates, another Muslim civil rights group, said Trump's comments "are abhorrent and simply have no place in the American public forum. We urge all Americans of good conscience to come together and rise above hate and extremist rhetoric that only serves to divide us at a time when we must stand together."

Trump strikes reflective tone

Trump's story took place during a rally in which the GOP front-runner reflected on his campaign's unanticipated success.

"This all began June 16. Who knew this was going to happen? I figured maybe I'd be in the pack," a subdued Trump said as he began his final rally before South Carolina's Republican primary on Saturday, which could hand Trump his second consecutive electoral victory. "I thought it was going to be like a horse race. I'd be in the middle of the pack and at the very end I'd inch it out."

But Trump isn't in the middle of the pack, ready to inch out a victory in South Carolina. He's leading it, with CNN's average of South Carolina polling showing Trump with a double-digit lead over his closest competitor, Texas Sen. Ted Cruz . The victory would be a momentous one for Trump and a blow to several of his opponents, including Cruz, who has positioned himself as the conservative capable of rallying the South to capture the nomination.

At Friday's rally, Trump ripped Cruz as someone "who lies more than any other human being I have ever seen" and slammed politicians broadly as "all taken care of by every industry."

And while Trump touted his 20-point victory just a week earlier in the New Hampshire primary, he also sought to undercut his supporters' -- and the media's expectations -- urging them not to look at the polling showing him poised to clutch a decisive victory, but instead to get out and vote like they were preparing for a nail-biter.

"Who knows what the numbers are. The polls are very nice. Who knows? We can't take a chance," Trump said in comments starkly in contrast with his predictions of a "tremendous victory" in Iowa the day he ultimately faltered with a second-place finish.

"It's crunch time, folks. It's crunch time," he reminded the audience.

But Trump ended the night on a reflective note, reminding his supporters that they are part of a movement of which he is simply the "messenger" -- and urging them to get out and vote.

"You're going to say to yourselves this was one of the greatest evenings and one of the great days of your lives," Trump said.

"We're going to make America great again. Thank you, everybody. I love you."