Martin Luther King's daughter said on Monday that "God can triumph over Trump", but the slain civil rights leader's son struck a conciliatory tone after meeting with the president-elect on the US holiday that honours their father.
The comments by the children of King, who championed racial justice until he was assassinated in 1968 at the age of 39, punctuated an imbroglio involving Donald Trump and African-American congressman John Lewis that broke out over the weekend.
The dispute started when Lewis, 76, a contemporary of King's who endured beatings and jail time in the civil rights movement of the 1960s, said in a televised interview that he saw Trump's election as illegitimate because of Russian interference in the campaign. That drew a scornful response from Trump.
Bernice King, King's youngest daughter, told a gathering at Ebenezer Baptist Church in Atlanta not to give up hope and "Don't be afraid of who sits in the White House."
"God can triumph over Trump," she said, drawing a standing ovation, one of several times she was interrupted by thunderous applause.
The service at the church where King once preached takes place every year on Martin Luther King Jr Day, a federal holiday honouring his life. This year the holiday fell days before Barack Obama ends his second term as the country's first African-American president. Trump takes the oath of office as his successor on Friday.
Obama and first lady Michelle Obama spent part of their last MLK Day in office helping paint a mural in the "community room" of a Washington shelter, to which they donated a play set used by their daughters when they arrived at the White House in 2009.
Trump, who won only eight per cent of the black vote, offered praise for King in a Twitter post on Monday, a few hours before meeting King's oldest son, Martin Luther King III, at his Trump Tower offices in New York.
"Celebrate Martin Luther King Day and all of the many wonderful things that he stood for. Honour him for being the great man that he was!" Trump tweeted.
Trump and King III emerged from an elevator together, shaking hands. Trump said goodbye to King, then returned to the elevator without answering questions.
King said they had a constructive meeting to discuss how to improve the US voting system, which King considers broken, but he skirted questions about whether he was offended by Trump's comments on Lewis.
"First of all I think that in the heat of emotion a lot of things get said on both sides. I think at some point I bridge-build. The goal is to bring America together," King told reporters.
Lewis did not mention Trump in a speech in Miami about the civil rights struggle to honour King, who would have turned 88 on Sunday, but he urged young black Americans to consider voting a "sacred" act.
"We all must become participants in the democratic process. When you get old enough to register to vote, go and register and vote," Lewis said in a half-hour address.
Gunfire during Miami holiday festivities wounded eight people ages 11 to 30 at Martin Luther King Jr Memorial Park, police said. Two people were detained and two weapons seized, and the cause of the shooting is under investigation.
Russian meddling
The Trump-Lewis exchange began when Lewis told NBC News in segments of an interview released on Friday that he would not attend Trump's inauguration in part because "I don't see this president-elect as a legitimate president".
He referred to the findings of US intelligence agencies that Russia used hacking and other methods to try to help Trump, a Republican, defeat Democrat Hillary Clinton in the November 8 election.
Trump was withering in his response the following day, saying in tweets that Lewis, a revered figure who risked his life for civil rights, was "All talk, talk, talk – no action or results."
While many Democrats and Republicans said they disagreed with Lewis, they also questioned Trump's decision to denigrate an African-American political leader of Lewis' stature, especially over the Martin Luther King Jr weekend.
Civil rights leaders have also opposed Trump's nominee for US attorney general, Senator Jeff Sessions of Alabama, who was denied a federal judgeship in 1986 after allegations that he was racist and harboured sympathies toward the Ku Klux Klan, a violent white supremacist organisation.
The Senate Judiciary Committee has received letters from 400 civil rights organisations opposing his confirmation to the country's top law enforcement post, Democratic Senator Dianne Feinstein has said. Sessions strongly denied that he is a racist during his confirmation hearing in the Senate last week.
