Clinton, Vermont Sen. Bernie Sanders and former Maryland Gov. Martin O'Malley sat down, one after the other, with MSNBC's Rachel Maddow for a half hour at Winthrop University. And despite never facing off directly onstage, the hits sounded sharper than they had before, even during the first Democratic debate hosted last month.
Sanders built on his new line of attack against Clinton on Friday night, playing off President Barack Obama's decision
just hours earlier to kill the Keystone XL pipeline.
"Now to me, as opposed to maybe some other unnamed candidates, the issue of Keystone was kind of a no-brainer. It never made sense to me, from day one, as to why you would extract and transport some of the dirtiest fuel on this planet," Sanders said, taking an implicit jab at Clinton, who consistently refused to say where she stood on the issue until recently.
Even O'Malley got in on the hits, saying Clinton got around to opposing the pipeline "just last week" (it was actually several weeks ago) while he, too, had been opposed for months.
"Yes, but Secretary Clinton got there just last week. And I was against it a year ago," O'Malley said. "I think it's important because I think leadership isn't about following polls."
O'Malley didn't train all his fire on Clinton, however. He also dinged Sanders for seeking a primary opponent to run against Obama in 2012.
O'Malley later brushed off questions of his hit on Sanders, after the forum. Sanders campaign manager Jeff Weaver said O'Malley "has to sort of lash out" at opponents, just as O'Malley walked into the spin room.
O'Malley parried Weaver's jab.
"Am I lashing out? I don't think I am lashing out. I am not trying to lash out," O'Malley said. "I think there are differences between the three of us. I have a great deal of respect for Sen. Sanders. I have a great deal of respect for Secretary Clinton. I am not running for president of the United States because I disrespect or dislike either of them. But there are fundamental differences between the three of us. ... I don't think the answer to this problem is socialism. I don't think the answer to this problem is to declare that all Republicans are our enemies."
Sanders, who promised not to go negative and has won support as a nontraditional candidate, argued he was not knocking Clinton.
He took some shots at media he said had been baiting him into hitting Clinton but he said he was trying to lay out differences with Clinton and not go negative.
But he quickly pivoted back to hitting her for reliance on a super PAC and top-dollar Democratic donors.
"I have many disagreements with Hillary Clinton, and one of them is that I don't think it is good enough to just talk the talk on campaign finance reform, you've got to walk the walk," Sanders said.
Clinton, who was last to speak Friday night, won some applause from the South Carolina crowd with her rebuttal.
"Anybody who thinks that they can influence what I will do doesn't know me very well," Clinton said.
Still, the success of Sanders in pulling the Democratic discussion leftward could not be avoided.
Clinton talked of her "New New Deal" and made an economic populist pitch -- albeit not as fiery as avowed democratic socialist Sanders.
"We are at a point in history right now where both our democracy and our economy are not working for the majority, they are working for a select minority very, very well," Clinton said.
The subtext of their trip to South Carolina, the third state in line to select a nominee, could not be avoided. Sanders, Clinton and O'Malley played up their support for black voters, who make up a major chunk of the electorate here.
O'Malley, who has struggled to gain traction in the field, even as other opponents have peeled off, made the clearest plea to black voters when asked what of the demands from the Black Lives Matter movement could be accomplished.
"I think that almost all of their agenda can get done," O'Malley said of the movement. But O'Malley was quickly rocked on his heels as he explained his own history presiding over the implementation of Zero Tolerance policing as mayor of Baltimore.
Sanders entered South Carolina on Friday with promises that he would begin executing his plan to reach black voters, but did not offer much in the way of details of how he would change his approach.
"I was there with Martin Luther King Jr., Dr. King, in the March on Washington," Sanders said as he played up his liberal bona fides.
Clinton, meanwhile, ticked down a list of stories of police violence on black residents.
"I still can't get over Eric Garner in New York died of a chokehold," she said.