Democratic presidential candidates Bernie Sanders, left, Hillary Rodham Clinton and Martin O'Malley participate in a Democratic presidential primary debate Nov. 14, 2015, in Des Moines, Iowa. (Charlie Neibergall/AP)

At a forum Saturday in South Carolina, Hillary Clinton sought to sharpen the distinctions between her candidacy for president and that of Vermont Sen. Bernie Sanders, who she said would raise taxes on the middle class.

Speaking to hundreds at the Charleston County Democratic Party’s Blue Jamboree — including many wearing T-shirts or toting signs supporting Sanders — Clinton suggested that Sanders’s health-care proposal would effectively raise taxes on the middle class and amount to a dismantling of President Obama’s signature health-care law — a notion that Sanders disputes.

“You know the deck is rigged, but we’ve got to reshuffle that deck,” Clinton said, speaking to the growing concern within her party’s base that the political and economic systems are skewed to benefit the rich and powerful. “And make sure we are raising incomes for the middle class, not raising taxes on the middle class. And I will not do that.”

All week, Clinton’s and San­ders’s camps traded barbs over middle-class taxes, an issue that Clinton’s campaign believes is a proxy for broader differences between the two candidates. Clinton’s stance highlights her focus on preserving President Obama’s health-care legacy, while Sanders has offered a proposal that seeks to make good on his promise of bringing a “political revolution.”

The Clinton campaign said that in Iowa this weekend, Clinton will build on her previously announced plans and propose additional tax cuts for middle-class families. But in campaign stops in Tennessee and South Carolina, she focused on health care and a plan to give middle-class families as much as $5,000 in tax credits for unexpected out-of-pocket health-care costs.

On Saturday, the Clinton campaign released two new ads, which will air in Iowa and New Hampshire, focused on her pledge to defend Obama’s health-care law.

“Other candidates want to increase taxes for the working people and the middle class as part of their health plans,” Clinton said Saturday. “Well, I don’t want to see your taxes go up, I want to see your health-care costs go down.

“We can manage to do that while preserving the accomplishment of the Affordable Care Act,” she said.

Sanders has proposed implementing single-payer, universal health care, which his campaign said would save families roughly $5,000 annually and would make a tax credit such as the one proposed by Clinton unnecessary.

The sharpening of the debate between the candidates on a key policy issue comes at a time when Sanders is ramping up his rhetoric and organizing efforts. The senator is in the midst of a three-day swing through South Carolina, a state where he lags far behind Clinton in the polls, as he acknowledged.

Some in the crowd had waited on their feet for hours after Sanders spoke to make their presence known during Clinton’s speech. They occasionally interjected with exhortations to “tax the rich” or protestations that corporate executives are “talking all our money.”

Presidential hopeful Hillary Clinton targeted health care costs and gun control at campaign event in Tennessee. (Reuters)

During his appearance here, Sanders pushed back at the assertion that Clinton’s health-care plan was better for the middle class and voiced full-throated support for moving to a “Medicare for all” system.

“I would hope every candidate would join me in saying finally, finally, health care must be a right for all people,” Sanders said in a not-so-thinly veiled jab at Clinton.

Speaking to reporters earlier, Sanders was more direct, saying that he was “disappointed” that Clinton would not back a system that would “save middle-class families thousands and thousands of dollars a year.”

Sanders also spoke dismissively of Clinton’s plan to offer tax credits to defray the cost of care.

“Well, I think everybody in America should be able to afford health care,” he told reporters. “You don’t need tax credits if you have a cost-effective health-care system. . . . I believe the United States should join the rest of the world with a Medicare-for-all, single-payer system.

During his remarks to the crowd, Sanders also reiterated his support for legislation pending in Congress that would mandate that employers provide three months of paid leave after a family has a child.

Clinton has said she supports paid family leave but has not embraced a bill introduced by Kirsten Gillibrand, Clinton’s successor as a senator from New York, that dozens of progressive lawmakers have lined up behind in both chambers of Congress.

The bill would be paid for by an increase in the payroll tax estimated to cost the average worker about $72 a year — a provision that violates Clinton’s pledge not to raise taxes on the middle class.

“When a working-class woman has a baby, she should not be forced to go back to work a week or two later,” Sanders said. “Some people may think the cost of that legislation — $1.39 a week — is too much. I don’t.”

Former Maryland governor Martin O’Malley, meanwhile, broadly escalated his rhetoric against his Democratic opponents. Laying claim to being the only candidate who is a lifelong Democrat, O’Malley accused Sanders of trying to implement socialism and Clinton of being beholden to Wall Street interests.

“There are differences in this race,” O’Malley said. “For a long time, watching the national news, I’m sure you thought you only had two choices. Well, guess what? You’ve got three. And we are not such a poor party that we can’t afford to have three choices.”