Thomson Reuters
Republican U.S. presidential candidate businessman Donald Trump responds to criticism from former Governor Jeb Bush as Senator Ted Cruz looks on during the Republican presidential debate in Las Vegas
Polls for the state's Republican primary close at 7 p.m. ET. Meantime, the candidates have spent the past 24 hours lighting into each other - and trading accusations of lying and using "dirty" campaign tricks.
Donald Trump, the frontrunner in the South Carolina polls, tweeted on Saturday morning: "Lying #Ted Cruz just (on election day) came out with a sneak and sleazy Robocall. He holds up the Bible but in fact is a true lowlife pol!"
Trump did not elaborate on what exactly he meant by "sneak and sleazy Robocall," but he's not the only candidate to accuse Cruz, the Texas senator, of such tactics.
Trump is leading all recent polls in South Carolina, with Cruz and Sen. Marco Rubio fiercely battling for second place. And with South Carolina having the potential to "reshape the 2016 contest," the candidates have become increasingly snippy on the campaign trail over the past week.
On Saturday, Rubio's campaign accused the Cruz campaign of making "false calls" that allegedly suggested the Florida senator would drop out of the Republican race.
"At last night's Clemson rally, a gentleman in the crowd fell ill and Marco brought the event to a close so medical personnel could respond," Rubio campaign adviser Joe Pounder said in a statement Saturday afternoon.
"Unfortunately, while Marco was leading the crowd in prayer, some were writing scripts for anonymous phone calls using the incident to suggest Marco was leaving the race," he continued. "These calls are false, malicious, and beneath the dignity of all South Carolinians."
Pounder called on Cruz to repudiate the calls. The Rubio campaign has not released any evidence of these calls, but Pounder said Cruz and his supporters have "flooded South Carolina with false and outrageous lies."
"In the past 24 hours, Senator Cruz and his allies have flooded South Carolina with false and outrageous lies," Pounder said in the statement. "Having realized he has run out of positions to flip flop on, Senator Cruz has settled on a strategy to steal elections through rumors and lies."
The Cruz campaign has been embroiled in a similar controversy before. During the Iowa caucuses, campaign workers called precinct captains in the state and implied that retired neurosurgeon Ben Carson was "suspending campaigning." The caller instructed precinct captains to tell Republicans to caucus for Cruz instead of Carson.
Meanwhile, the campaign of former Florida Gov. Jeb Bush has accused Rubio's campaign of lying about those calls.
Bush campaign manager Danny Diaz tweeted on Saturday that Rubio should "launch a truth squad against his own campaign." That came in response to a tweet from Bush's communications director, Tim Miller, who said the campaign has "reports of Rubio campaign spreading lies about Jeb & [Ohio Gov. John] Kasich at precincts on the coast."
And as Trump looks poised to win the state, Politico noted that high-level Republicans seem eager for low-polling candidates to drop out so that establishment donors can consolidate behind an alternative to Trump.