Buttigieg initially planned to skip a high-profile event on Monday in Columbia, only be denounced as "disrespectful" by a state legislator. The former South Bend, Ind., mayor then switched his plans and attended at the last minute. Even so, he was reduced to a non-speaking role while his rivals delivered impassioned speeches.

Buttigieg then raced to Iowa and the quadrennial Brown & Black forum, where he faced tough but familiar questions from young journalists and skeptical attendees. Pressed on the lack of diversity in the South Bend Police Department when he was mayor, Buttigieg said it was "an area where I've admitted it's not where I wanted to be."

Buttigieg may have had the toughest day, but the Martin Luther King Jr. Day events, coming two weeks before the Iowa caucuses on Feb. 3, highlighted an increasingly tense relationship between the black community and the Democratic Party overall, despite the urgency of their joint desire to defeat President Trump.

Young activists from Black Lives Matter and other movements increasingly show deep skepticism about the Democrats' plans and their ability to deliver them. Two prominent black candidates who started with high hopes — Sens. Kamala D. Harris (D-Calif.) and Cory Booker (D-N.J.) — were forced to drop out, as Democrats, African American and otherwise, seek the candidate most likely to defeat Trump.

The top tier of the Democratic primary is all white. Critics of the Iowa caucuses, the first nominating contest, say the state's largely white electorate does not reflect the country. Another candidate, former New York mayor Mike Bloomberg, has been attacked for racial insensitivity during his own tenure as mayor.

Those tensions, as well as the efforts to bridge them, were on display Monday as candidates joined with black leaders to celebrate a civil rights icon who had his own fraught relationship with the Democratic Party.

In South Carolina, the candidates quoted scripture and gospel singers and, of course, King. They linked arms and marched behind an NAACP banner and then, one by one, told an army of black faces why their vision for the presidency was an extension of King's dream.

In its 20th year, King Day at the Dome — a march to the steps of South Carolina’s state Capitol on Martin Luther King Jr. Day — served a dual purpose of celebrating the United States’ civil rights past and informing its political future. The event is one of the last high-profile opportunities for presidential candidates to make their pitch to black voters before the state’s first-in-the-South primary here on Feb. 29.

Black voters make up nearly two-thirds of Democratic primary voters in the state. Their votes have handed primary wins to the past two Democratic nominees — Barack Obama and Hillary Clinton — in a state that many believe will be a bellwether for how black people across the United States will vote.

The crass political implications of the event can be at odds with a march that, for most of the past two decades, celebrated uplift and solidarity in the face of common struggle. As candidates marched from a Columbia church to the state House, their supporters could not decide whether to chant campaign slogans or to sing “We Shall Overcome.”

Later, on the steps of the state Capitol, the Democratic contenders spoke broadly of the need to complete King’s unfinished work while also touting their own particular plans for addressing racial inequality.

Former vice president Joe Biden, who has been leading the polls in South Carolina by a large margin, spoke of the racial progress that occurred when he served under Obama, the first black president. He told the crowd that, with this election, “we have a chance to rip out the roots of systemic racism in this country.”

“The Bull Connors of today don’t stand in the street with fire hoses and dogs,” he said, referring to the infamous segregationist. “They wear nice suits. They wield their power rolling back rights, punishing the poor, denying access to health care and quality education and turning away refugees and asylum seekers.”

Biden added: “It’s not snarling dogs that’s part of this inflection point — it’s Donald Trump’s poisonous, divisionist politics.”

Biden’s top rivals in South Carolina, Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.), told voters that the explicit racism King and other civil rights luminaries battled has in many ways been replaced by racial disparities that are now baked into the country’s economic and political systems.

Buttigieg was initially chastised for not attending the dome event, particularly because he has struggled to attract the support of black voters.

“I’m putting this out there: candidates skipping King Day at the Dome is disrespectful,” Bakari Sellers, a former South Carolina state legislator who endorsed Sen. Kamala D. Harris (D-Calif.) before her departure from the presidential race, tweeted on Friday. “You don’t miss an Iowa steak fry. Look, you’re not just speaking to black folk in S.C. you’re speaking to black folks throughout the South. I’m disappointed. It’s like you don’t care.”

Buttigieg scrambled to change his schedule. He took part in the march but was not mentioned in the program of speakers, nor did he address the crowd at the Capitol steps.

Tensions were more visible after the South Carolina event ended and the Brown & Black Forum unfolded in downtown Des Moines.

Buttigieg, one of four candidates who flew from Columbia to Des Moines, faced familiar and nagging questions about how he had handled complaints from black police officers during his eight years as mayor of South Bend. Buttigieg called it a “painful issue,” but he added that he “met and spoke with black officers all the time” and that the criticisms lacked context.

“I saw to it that that board not only was diverse but actually majority African American, because these racial questions are so important,” Buttigieg said. “I get a lot of questions about why I removed a black police chief. Almost never do I get a question about why I appointed a black police chief in the first place. It was largely because of his expertise and strength when it came to community policing.”

Sen. Michael F. Bennet (D-Colo.), who has largely focused his campaign on New Hampshire, was asked why candidates of color were no longer making it into the debates. “I’m doing my part,” Bennet joked, “because I didn’t qualify for the last debate.”

Bennet, who tried to steer the conversation back to his work as a schools superintendent and his child-friendly tax policies, was also asked why he had not joined the other candidates in South Carolina.

“To be totally candid with you, I miss not being there today,” Bennet said, adding that his campaign schedule and limited resources made it impossible.

King Day at the Dome started in 2000 as a grass-roots protest after South Carolina legislators voted to keep the Confederate battle flag waving above the state House dome.

Black religious leaders, the NAACP and the National Urban League rallied support across the state, and some 46,000 people marched to the north-facing facade of the Capitol that first year.

Subsequent marches occurred as the Confederate flag declined in prominence at the state House. It was moved to a flagpole at a Confederate Memorial on the Capitol grounds in 2000. And after the race-based killing of nine parishioners at a historically black Charleston church in 2015, the flag was relocated to a museum.

But King Day at the Dome marches continued, becoming important events for those seeking support in the South Carolina primary.

Jeffrey Lites, 56, of Lexington, S.C.,

who has been attending the event for 20 years, said he doesn’t think the infusion of presidential politics has corrupted the event’s essence.

“This,” he said, gesturing to the speaking politicians, “is also a civil rights issue of our time. President Trump is dividing the country, pitting people against each other. What’s more important than black people voting for the right president?”