COLUMBIA, S.C. — Several Democratic presidential candidates briefly put aside their recent sparring on Monday and marched arm in arm through the streets of South Carolina’s capital to honor the Rev. Dr. Martin Luther King Jr., whom they later invoked in speeches about America’s past and future that were rich with election-year overtones.
As the six-block march began from the Zion Baptist Church to the State House, where a Confederate flag once flew over the dome, Senator Bernie Sanders looped an arm through Senator Elizabeth Warren’s elbow, as the two joined other candidates in singing “We Shall Overcome” for part of the trip. Representative Tulsi Gabbard and Senator Amy Klobuchar each locked elbows with former Vice President Joseph R. Biden Jr. as well.
The sight of Mr. Sanders and Ms. Warren shoulder to shoulder — after a week in which they argued over their recollections of a private conversation about whether a woman could win the presidency — delighted Lisa Ray Clarkson, a retired teacher from Norfolk, Va., who was at the march.
“That means they have gotten over their differences and the Democratic Party is reuniting,” Ms. Clarkson said as she walked alongside the procession to the State House, where several thousand people converged.
It was a hopeful sentiment for a Democratic field that has become noticeably more fractious in the final weeks before the Feb. 3 caucuses in Iowa, where Mr. Biden, Ms. Warren, Mr. Sanders and former Mayor Pete Buttigieg of South Bend, Ind., are bunched tightly in polls and planned to campaign on Monday afternoon.
In addition to the Warren-Sanders argument, Mr. Biden and Mr. Sanders have been criticizing each other’s records, with Mr. Sanders trying to cut into Mr. Biden’s support among older voters and black voters by portraying the former vice president as open to cuts in Social Security. Mr. Biden has denied that and demanded an apology from Mr. Sanders, who has stood firm.
The four candidates are also competing hard in South Carolina, particularly for support from black voters, who will make up a majority of the Democratic primary vote in the state on Feb. 29. Mr. Biden has a strong lead in South Carolina polls and is widely favored among black voters. None of his rivals took him on frontally on Monday, but instead sought to make the case to African-Americans and others in South Carolina about how the next president could benefit their interests.
Mr. Sanders, addressing the enthusiastic crowd on a cold day at the State House, reminded onlookers of Dr. King’s legacy of courage and opposition to the Vietnam War, which the 78-year-old Vermont senator also denounced. While Mr. Sanders has been trying to draw a contrast with Mr. Biden on their records on military action, he focused more on Monday on President Trump.
“If we do not allow Trump and his friends to divide us up by the color of our skin, or where we were born, or our sexual orientation or religion, if we stand together there is nothing we cannot accomplish in the fight for racial justice, social justice,” Mr. Sanders said.
Ms. Warren, of Massachusetts, told the gathering that the nation was ready “to write the next chapter of our history.”
“The next chapter — that will be an America where health care is a basic human right, that will be an America where safe and affordable housing is available and no one sleeps on the street, that will be an America where people trying to get an education will not be crushed by student loan debt,” she said.
Ms. Klobuchar, of Minnesota, invoked Dr. King’s comment that Americans are “all tied in a single garment of destiny — what affects one directly affects all indirectly,” and said that rising hatred across the nation would ultimately wound everyone.
“It coarsens our civic life. You can see it in the senseless racist shooting of worshipers in Charleston, you can see it in that rabbi’s home and stabbing, you see it in that bombing of the mosque in Minnesota, you see it at the riot in Charlottesville,” she said.
Addressing Mr. Trump directly over his comment in 2017 that “both sides” were to blame for the violence in Charlottesville that killed Heather Heyer, who was protesting a white supremacist rally there, Mr. Klobuchar said: “And no, there are not many sides to blame, Mr. President, when one side is the Ku Klux Klan. There is only one side, and that is the American side. That is it. That is all.”
Before the march and State House speeches, several candidates told a breakfast gathering of predominantly black voters that they were committed to advancing Dr. King’s legacy and that defeating Mr. Trump in November was a crucial step toward that goal.
“My campaign revolves around the image of the first day that the sun comes up over South Carolina and our country and Donald Trump is no longer the president of the United States,” Mr. Buttigieg said at the Columbia Urban League’s annual King breakfast. “I raise the image of that sunrise because it will bring forth the burning question Dr. King posed in the summer of 1967: Where do we go from here?”
“Because on that day our country will be even more polarized and torn up than it is now,” said Mr. Buttigieg, who is one of the top-polling candidates in Iowa but is struggling in South Carolina and among black voters. He urged action to combat disparate treatment by race in the health care system and to address environmental pollution disproportionately affecting African-Americans, who make up a majority of the Democratic primary electorate in the state.
Tom Steyer, the billionaire businessman who polled at 15 percent in South Carolina in a recent Fox News survey, tying him with Mr. Sanders for second place, called on Americans to “channel Dr. King” and take action against a government that he described as hostile to the hungry and others in need.
“Every political issue that I see in the United States of America has a subtext that’s race,” Mr. Steyer said. “It may be awkward. It may be uncomfortable, but we have to have that conversation. I believe that out of narrative comes policy.”
Former Gov. Deval Patrick of Massachusetts, the only black candidate still in the Democratic field, took a different tack, telling the breakfast audience, “If we are really going to deliver a future for our children and grandchildren consistent with the values of equality, opportunity and fair play, to which Dr. King and the Urban League served as examples, then we’re going to have to start rejecting false choices.”
“Prosperity and justice can live alongside each other,” he said. “The notion that you have to hate business to be a social justice warrior or hate police to believe black lives matter are ridiculous.”
Mr. Biden said that Mr. Trump’s conduct and record in office — including his remarks that gave a boost to white supremacists after the Charlottesville rally — had led to an “inflection point in the civil rights movement.”
“We have a president who embraces white supremacists, who rips families away at the border,” Mr. Biden said. “We have to work together twice as hard to get out of the situation we find ourselves in.”
“God willing, we can turn four years of Donald Trump into an historical aberration,” he added.
After the South Carolina events, most of the candidates planned to fly quickly to Iowa to attend the 2020 Iowa Brown & Black Democratic Presidential Forum on Monday afternoon.
At a breakfast honoring Dr. King in Washington, D.C., former President Bill Clinton delivered a message casting the diversity of America as one of the country’s biggest strengths. But he also noted that a diverse nation functions well only if everyone follows “the same set of rules,” making an oblique nod to Mr. Trump as well as to Republican efforts to make it harder for some communities of color to cast their ballots.
“America, at its best, is a country of inclusive tribalism,” he told an audience of black leaders, public officials and activists. “Our churches, our synagogues, our mosques or temples, we like diversity but it only works if you think our common humanity matters more.”
“There are 15 issues we should be fighting about, but at the core is universal easy access to vote where the votes count,” he said. “And a vigorous attempt to stop foreign influence.”
Mr. Clinton was in Washington to accept an award at a breakfast hosted by the National Action Network, the organization founded by the Rev. Al Sharpton.
Jonathan Martin contributed reporting from Columbia, S.C., and Lisa Lerer from Washington.